English: The formulaic language of time-series comparisons

Tracking economic trends by comparing data with earlier periods is a staple of economic analysis. There are many possible ways of expressing this. For example, in spoken English it would be perfectly natural to say:

We sold 6% less this month than we did last month.

Such comparisons occur so frequently in economic prose that they have come to be expressed in formulaic patterns. While English is remarkable for the number of formulas in use, at base they tend to conform with what I will call the "Standard Pattern":

Sales in June decreased 6% compared with the previous month.

Compared with our hypothetical example of spoken English, this format has the following features:

Parameters are expressed as nouns (that is, 'the volume or value of sales' in preference to 'we sold').

Change in parameters is expressed in an impersonal manner as having 'taken place'. In this format, the neutral choice is intransitive verbs like 'increase' and 'decrease'.

The notion of 'comparison' is expressed explicitly.

Time periods are made explicit and fall into an organised system, e.g., 'the previous month', 'the same period of the previous year', etc. Time expressions related to the present time (e.g. 'last month') are avoided in favour of objective time periods related to the period in question ('the previous month').

The "Standard Pattern" appears to be shared by many languages. What's exceptional about English is the range of choices and variations that are found within that format. English also uses a couple of other grammatical patterns, although they are less common than the "Standard Pattern".

Here we look more closely at the many different forms that "Standard Pattern" takes in English.

Building up the Basic sentence

The Standard Pattern in English goes like this (colour coding is here , hover to see):

Sales in June decreased (by) 6% compared with the previous month.

Breaking this sentence into its components gives us a baseline for understanding variation in English and comparing it with other languages.

Click on each button to identify the elements of the sentence below.

A. The subject is the metric ('sales' = value of sales). Subject

B. The current time period is shown by a prepositional phrase. Current Period

C. Direction of change is shown by an intransitive verb. Verb

A B C
Sales
in June
decreased

The sentence is then expanded by adding elements after the verb.

D. The change is quantified by an adjunct (6%), optionally preceded by the preposition 'by'. Quantification

E. Comparison is indicated by a participial clause, using the past participle of the verb 'to compare'. Comparison

A B C D E
Sales in June decreased
(by) 6%
compared with the previous month

The participial clause is the condensed form of a conditional clause ('if they are compared with') or time clause ('when they are compared with'). 'Compared' is passive -- that is, it is abbreviated from 'to be compared'. The passive indicates that a comparison is being made without identifying the person making it. (info)

Word order: This sentence exemplifies the neutral word order: the main clause ('sales decreased') first, followed by other elements after the verb.

In the next tab we'll look at ways of describing change in the metric.

Describing Change

Apart from 'no change', which we don't discuss here, change involves two possibilities: an increase or a decrease.

English offers two options for expressing this. The first is the totally unremarkable use of intransitive verbs. The second is much more specific to English: the use of 'be' plus an adverb or preposition.

SUMMARY

Subject Change Quantif. ...
Sales decreased (info)
were down (info)
(by) 6% ...

 

EXPLANATION (Click buttons to see content)

Using a verb

The standard choice is an intransitive verb, exemplified by 'decreased' in the following sentence:

Sales in June decreased (by) 6% compared with the previous month.

The verb used will often depend on the style of writing.

a) Most common are neutral verbs like 'to increase' or 'to decrease', and close synonyms like 'to rise' and 'to fall' or 'to expand' and 'to contract'. These are preferred in formal papers or business presentations.

b) In spoken English, more informal expressions may be heard, such as 'to go up' or 'to go down'.

c) Journalists tend to choose 'colourful' verbs like 'to soar', 'to shoot up', 'to edge up', 'to plummet', 'to sink', 'to plunge' etc. to liven up their prose. These are generally avoided in more sober writing.

Using a preposition/adverb

'Up', 'down' and 'off' are frequently used to describe change. They are technically adverbs in this case, but it's hard to pin down what part of speech they belong to (Note). Here we'll concentrate on how they are used in sentences like the following:

Sales in June were down 6% compared with the same month of the previous year.

Although on the colloquial side, this usage is widely favoured for its brevity and versatility.

Quantification of the change (6%) comes either before or after the preposition. If placed before, 'by' is omitted.

Subject Verb 'to be' Preposition/adverb Quantif.
Sales were down (by) 6%

OR

Subject Verb 'to be' Quantif. Preposition
Sales were 6% down

Next we look at the means of expressing the comparison.

Expressing the Comparison

English uses a few different expressions to indicate the comparison, including (again) prepositions. The table below summarises the choices available:

Subject Intransitive verb Comparison indicator Period of comparison
Sales fell compared with (info)
over (info)
in comparison with (info)
the previous month

 

EXPLANATION (Click buttons to see content)

Using 'compared'

The most straightforward method is to use the participial phrase 'compared with', consisting of the past participle of 'compare' plus the preposition 'with'.

Subject Intransitive verb Clause of comparison
    Comparison indicator Period of comparison
Sales fell compared with the previous month

For example:

Sales in June were off (by) 6% compared with the previous month.

Interest rates declined 0.6% compared with the previous quarter.

The structure can be understood as abbreviating a conditional clause ('if sales are compared with') or a time clause ('when sales are compared with').

It's also related to 'as compared with', which has the grammatical peculiarity that the subject and auxiliary verb ('they are') must be omitted:

Sales in June fell (by) 6% as compared with the previous month.

In each of these cases, 'compared with' represents an abbreviation of the passive form 'be compared with'. The passive voice is frequently used in English as a way of omitting the agent in cases where it isn't important to identify exactly who is doing the comparing.

Using prepositions

A popular alternative is to use simple prepositions such as on, over, from, and (less commonly) against. These condense the comparison into a short, simple prepositional phrase. These prepositions give a colloquial, 'dynamic' feeling.

Subject Verb Complement Prepositional phrase
      Preposition Period of comparison
Sales decreased (by) 6% over the previous month

'On', 'over', and 'against' indicate a juxtaposition of the present with the past. 'From' indicates a change from past to present.

Examples:

Sales in June fell (by) 6% over the previous month.

Sales in June plummeted (by) 6% on the previous month.

Sales in June declined (by) 6% against the previous month.

Sales in June slumped (by) 6% from the previous month.

A preposition/adverb indicating change and a preposition indicating comparison may come together in sequence:

Sales were 6% down on the previous month.

Some combinations are more common than others. For instance, ‘be down 6% on the previous month’ is probably more likely than ‘fall 6% on the previous month’.

More formal expressions

Another set of relatively formal expressions function like 'fancy prepositions'. They include common expressions like 'relative to' and 'in comparison with/to' as well as uncommon ones like 'versus' and 'vis-à-vis'.

Subject Intransitive verb Prepositional phrase
    Comparison indicator Period of comparison
Sales fell in comparison with the previous month

They are more appropriate to formal language.

Sales in June fell by 6% relative to the previous month.

Housing approvals increased by 6% in comparison with the previous quarter.

Period of Comparison

In economics, past periods fall into two types: the immediately preceding period (month, quarter), and the corresponding period of the previous year.

SUMMARY

COMPARISON WITH THE PREVIOUS PERIOD

Subject Intransitive verb Quantif. Comparison indicator Period of comparison
Sales fell 6% compared with the previous month (info)
May (info)

COMPARISON WITH THE SAME PERIOD OF THE PREVIOUS YEAR

Subject Intransitive verb Quantif. Comparison indicator Period of comparison
Sales fell 6% compared with the corresponding month of the previous year (info)
the previous year's month (info)
a year earlier (info)
June 20xx (info)

PERIOD EXPRESSED AS END POINTS

Subject Intransitive verb Quantif.   Period of comparison   Current period
Sales fell 6% from June 20xx to June 20yy

 

 

EXPLANATION (Click buttons to see content)

The immediately preceding period

Comparison with the immediately preceding period is straightforward:

Sales in June decreased (by) 6% compared with the previous month.

Sales in the April-June quarter decreased (by) 6% compared with the prior quarter.

'Prior', 'preceding', or 'previous' may all be used to refer to this period, which is usually a month, quarter, half-year, or year, but could be as short as a week or day. It's also not uncommon to spell out the preceding time period. For instance:

Sales in June expanded by 6 percent from May.

Sales in the second quarter expanded by 6 percent over the first quarter.

The same period of the previous year

Comparison with the corresponding period of the preceding year is more cumbersome. This is especially apparent in sentences like:

Sales in June decreased (by) 6% compared with the corresponding month of the previous year.

'Same' can be substituted for 'corresponding', but this has little effect on the general clunkiness of the sentence.

Not surprisingly, people have come up with a number of shorter ways of expressing this. They include:

‣ Condensed time reference

a) Condensed formats substitute expressions like 'the previous year's month' or 'the prior-year quarter'.

While grammatically somewhat clumsy, they are succinct and are widely found in business and journalistic prose, especially in North America:

Sales in June fell by 6% compared with the year-ago quarter.

Sales in June fell 6% over the prior-year quarter.

Sales in June fell 6% over the year-ago period.

‣ Underspecified time format

b) Even greater brevity can be achieved by underspecifying the time frame, that is by omitting the expression 'corresponding period' or 'same period' altogether:

Sales in June expanded by 6 percent from a year earlier.

Sales in June declined 6 percent from last year.

Sales in June fell by 6 percent from the year before.

This relies on context to indicate that the period of comparison is June of the previous year.

‣ Spelling out the period
c) It may be shorter to spell out the specific time period, which can also help add variety to prose.

Sales in June expanded by 6 percent from June of 2011.

The time period may be further abbreviated in ways mentioned above, e.g. through underspecification:

Sales in June expanded by 6 percent from 2011.

'Outside the box'

Under the "Standard Pattern" we've been using so far, references to time periods adhere to the following format:

Sales in June fell (by) 6% compared with the same period of the previous year / the prior year / the year-ago month.

However, the change from a prior period to the current period may sometimes be expressed with a different format. For example:

From June 2011 to June 2012, sales fell by 6%.

Rather than identifying the 'current period' and indicating how it compares with a 'prior period', it simply indicates the two periods as the two ends of a time range. This is a very uncommon pattern.

Shorthand format

Besides the choices above, English has a widely used Shorthand Format. This is based on using prepositions to indicate comparison.

This format appears to have originated in specialist usage (statistics or economics jargon), but is now widespread throughout the English-speaking world. The Shorthand Format, along with an abbreviated form of it, is summarised below.

SUMMARY

Subject Intransitive verb Quantif. Shorthand comparison
Sales fell (by) 6% year-on-year (info)
on-year (info)

 

EXPLANATION (Click buttons to see content)

Full shorthand form

The Shorthand Format follows the pattern ‘period-on-period’, also found as ‘period-over-period’ or, less commonly, ‘period-to-period’. The hyphens may be omitted, giving ‘period on period’ etc.

In some contexts (e.g., tables) this can be further abbreviated to ‘MOM’, ‘QOQ’, ‘YOY’, or ‘mom’, ‘qoq’, ‘yoy’.

The first noun in each pair can be understood as the current period; the second is the period of comparison. The preposition in the middle (‘on’, ‘over’, ‘to’) indicates the comparison.

The Shorthand Format functions as a sentence adverb and, like other formats, it comes after the quantification.

For comparison with the immediately preceding period (e.g., previous quarter or previous month), this format spells out the period. While this is usually ‘month’ or ‘quarter’, it can potentially also be ‘week’, ‘day’, etc. For example:

Sales in June fell by 6% month-on-month.

Sales in the 2nd quarter fell by 6% quarter-on-quarter.

For comparison with the corresponding period of the previous year (annual change), this format uses ‘year-on-year’. The precise period in question is generally obvious from the context. For example, this sentence clearly indicates comparison with June of the previous year:

Sales in June fell by 6% year-on-year.

The popularity of this format can be explained by its compactness, ease of comprehension, flexibility, and its amenability to further abbreviation.

Abbreviated shorthand form

The Shorthand Format can be further abbreviated by omitting mention of the first time period. This yields the form ‘on-period’ (e.g., ‘on-month’, ‘on-year’). The prepositions ‘over’ and ‘to’ are not used in this format.

Sales in June fell by 6% on-year.

It may also be found in the form:

Sales in June fell by 6% on the year.

The abbreviated format is not as common as the Full Shorthand Format.

‘At an annual rate’

Another approach is to use ‘at an annual rate’:

Sales decreased at a 6 percent annual rate during the first quarter of 2015.

Since this is an annual rate, it implies a year-to-year change rather than quarter-to-quarter change.

‘A 6 percent annual rate’ may be replaced by ‘an annual rate of 6 percent’:

Sales decreased at an annual rate of 6 percent during the first quarter of 2015.

Omitting the comparison

In its striving for simplicity and brevity, English may completely omit information concerning the comparison. For example:

New vehicle sales in June fell by 6%.

This certainly achieves the desired effect, but runs the risk of ambiguity and uncertainty. Omission is only advisable under certain conditions.

 

EXPLANATION (Click buttons to see content)

Context

The comparison can be omitted where the previous period is obvious from the sentence context. A simple example is the following, where the second metric (output) clearly refers to the same period as the first:

Sales fell by 6% compared with the same quarter of the previous year while output declined by 2%.

This can be represented as follows:

Subject Intransitive verb Quantif. Comparison indicator Period of comparison
Sales fell by 6% compared with the same quarter of the previous year
while
Output declined by 2% compared with the same quarter of the previous year

Previous year as default

Comparison can be omitted where the previous year is the default interpretation. When discussing annual economic growth, the comparison is usually with the previous year unless otherwise indicated. For example, ‘growth’ in the following sentence is understood as being compared with 2010 and may be omitted:

The economy grew by 6% in 2011.

The same applies to expressions like ‘in the year to date’ or ‘in the first eight months of the year’, which are usually interpreted as being compared with the same period of the previous year.

The economy grew by 6% in the year to date.

Unit costs increased 0.6% over the last four quarters.

The second sentence is referring to a one-year period (four quarters), which is being compared with the previous one-year period.

Ambiguous cases

There are, however, cases where the comparison information is omitted completely even when the result is ambiguous. For instance, journalists have been known to write sentences like:

Sales in June fell by 6%.

This will usually be intended to mean ‘the same period of the previous year’.

On the other hand, some organisations (specifically statistical organisations) adopt comparisons with the previous period, e.g., ‘quarter-to-quarter’, as the default.

Understanding the intended period of comparison may require familiar with the usual practice of the writer or organisation.

Other patterns

The "Standard Pattern" is based on intransitive verbs. Three other grammatical patterns are found for expressing comparisons:

1) Change expressed through the comparative degree of adjectives (‘higher’ or ‘lower’). This uses 'than’ to point to the period of comparison;

2) Verbs like ‘to exceed’ that don't need any kind of ‘comparison indicator’ since they directly link to the period of comparison, and

3) Prepositions like ‘above’ and ‘below’, which also directly link to the period of comparison.

 

 

Adjectival pattern (Click buttons to see content)

The Adjectival Pattern expresses change or difference by means of an adjective in the comparative degree, most commonly ‘higher’ and ‘lower’. Comparison is indicated by ‘than’.

Quantification usually comes before the comparative adjective, although it may be placed at the end of the sentence as ‘by 6%’.

Sales in June were 6% lower than the previous month.

This can be represented as follows. The period of comparison is expressed in the same way as the Standard Pattern:

COMPARISON WITH THE PREVIOUS PERIOD

Subject Current period Verb 'to be' Quantif. Comparative adjective Period of comparison
Sales in June were 6% lower (info) than the previous month (info)
than May (info)

COMPARED WITH THE SAME PERIOD OF THE PREVIOUS YEAR

Subject Current period Verb 'to be' Quantif. Comparative adjective Period of comparison
Sales in June were 6% lower (info) than the same month of the previous year (info)
than the previous year's month (info)
than a year earlier (info)
than June 20xx (info)

In this format, the period of comparison is fixed in position. It cannot be moved to the start of the sentence.

Note: ‘higher’ and ‘lower’ can also be used with the Standard Pattern:

Sales in June were 6% lower compared with the same month of the previous year.

However, they cannot be used with prepositions such as ‘on’ or ‘over’. In such cases, ‘than’ must be used:

Sales were 6% higher over the previous month.

Transitive verb

A relatively rare construction involves using the transitive verb 'to exceed'. This does not require a 'comparison indicator' because the verb itself makes a direct noun-to-noun comparison. For example:

Sales in June exceeded those for the same period of the previous year by 6%.

The period of comparison is expressed in a similar way to that of the Standard Pattern. The Shorthand Format can't be used.

COMPARISON WITH THE PREVIOUS PERIOD

Subject (metric) Current period Transitive verb Object (metric) Period of comparison ...
Sales in June exceeded those for the previous month (info)
May (info)
by 6%

COMPARED WITH THE SAME PERIOD OF THE PREVIOUS YEAR

Subject (metric) Current period Transitive verb Object (metric) Period of comparison ...
Sales in June exceeded those for the same month of the previous year (info)
the previous year's month (info)
a year earlier (info)
June 20xx (info)
by 6%

'By' is obligatory in the quantification. The above example is a direct comparison between periods ('sales in June' vs 'those for a year earlier'). It's also possible to omit 'those for', putting it in line with other patterns:

Sales in June exceeded the same period of the previous year by 6%.

Prepositional phrase

Prepositions such as 'below' or 'above' do not require a 'comparison indicator':

COMPARISON WITH THE PREVIOUS PERIOD

Subject (metric) Current period Transitive verb Quantif. Object (metric) Period of comparison
Sales in June were 6% below the previous month (info)
May (info)

COMPARED WITH THE SAME PERIOD OF THE PREVIOUS YEAR

Subject (metric) Current period Transitive verb Quantif. Object (metric) Period of comparison
Sales in June were 6% below the same month of the previous year (info)
the previous year's month (info)
a year earlier (info)
June 20xx (info)

The Shorthand Format can't be used with this pattern.

Sentence patterns summarised

The various frameworks discussed above are summarised in the following tables:

STANDARD PATTERN

Subject   Change Quantif. Comparison indicator Period of comparison
Sales in June fell (info)
were down (info)
were lower (info)
(by) 6% compared with (info)
over (info)
in comparison with (info)
the previous month (info)
May (info)
the same month of the previous year (info)
the previous year's month (info)
a year earlier (info)
June 20xx (info)
year-on-year (info)
on-year (info)
OMIT

VARIANT PATTERN INDICATING TIME RANGE

Subject Change Quantif.   Period of comparison   Current period
Sales fell (info)
were down (info)
(by) 6% from June 20xx to June 20yy

ADJECTIVAL PATTERN

Adjectives in the comparative degree can be used with 'than', or in the Standard Pattern (as shown above).

Subject Current period Verb 'to be' Quantif. Comparative adjective Comparison indicator Period of comparison
Sales in June were 6% lower (info) than the previous month (info)
May (info)
the same month of the previous year (info)
the previous year's month (info)
a year earlier (info)
June 20xx (info)

TRANSITIVE VERB PATTERN

Subject (metric) Current period Transitive verb Object (metric) Period of comparison ...
Sales in June exceeded (those for) the previous month (info)
May (info)
by 6%
the same month of the previous year (info)
the previous year's month (info)
a year earlier (info)
June 20xx (info)

PREPOSITIONAL PATTERN

Subject (metric) Current period Transitive verb Quantif. Object (metric) Period of comparison
Sales in June were 6% below the previous month (info)
May (info)
the same month of the previous year (info)
the previous year's month (info)
a year earlier (info)
June 20xx (info)

Word order

The word order used so far is the 'neutral' order, but English is relatively fluid in placinf various elements in the sentence. Word order can be varied for emphasis or sometimes just for stylistic reasons. The following shows some of the options.

 

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Placing of current period

English generally prefers a prepositional phrase to indicate the current period, usually attached to the noun:

Subject Current period Intransitive verb Quantif. Participial Clause (Comparison)
Sales in June decreased (by) 6% compared with the same month of the previous year

However, it can also be placed elsewhere in the sentence, with varying degrees of naturalness:

1 In June sales decreased (by) 6% over the previous month
2 Sales in June decreased (by) 6% over the previous month
3 Sales decreased in June (by) 6% over the previous month
4 Sales decreased (by) 6% in June over the previous month
5 Sales decreased (by) 6% over the previous month in June

In 1, 'in June' is topicalised as a sentence adverb by being placed at the start of the sentence.

In 2, it is a complement to the noun ('sales that took place in the month of June').

In 3, it attaches to the verb and tells when the decrease took place.

In 4, it also attaches to the verb, but the placement after the complement of quantification is less natural.

In 5, it can be regarded as either attaching to the verb as a sentence adverb. This order is less natural.

4 and (particularly) 5 become considerably less natural if a long form like 'in comparison with the same month of the previous year' is used.

Besides a prepositional phrase, the current time period can also be used to directly modify the noun, especially in more concise or journalistic styles:

Current period (modifies noun) Metric (subject) Intransitive verb Quantif. Participial Clause (Comparison)
June sales decreased (by) 6% compared with the previous month

Placing of quantification

Quantification can only be placed after the verb. When separated from the verb, 'by' is obligatory.

1 Sales in June decreased (by) 6% compared with the previous month
2 Sales in June decreased compared with the previous month by 6%

Placing of comparison

For the Standard Pattern and the Shorthand Format, the neutral position for the clause or phrase of comparison is at the end of the sentence (as in 4). However, it can be highlighted or topicalised by being placed at the start of the sentence (see 1). In other positions (2 and 3) it is less natural and 'by' is obligatory.

1 Compared with the previous month
Month-on-month
sales fell (by) 6%
2 Sales compared with the previous month
month-on-month
fell by 6%
3 Sales fell compared with the previous month
month-on-month
by 6%
4 Sales fell (by) 6% compared with the previous month
month-on-month

Integration into the sentence

Besides word order, expressions of comparison are well integrated into the broader sentence. The following are just a few examples.

 

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Verb + nominalisation

One favoured device in English prose is to the use of a 'verb + nominalisation' combination instead of a simple verb. This involves nominalising the verb (converting it into a noun) and linking it up with another verb.

For example, instead of 'to decrease', English may use expressions like 'to show a decrease' or 'to register a decline':

Sales in June showed a 6% decrease compared with the previous month.

This can be represented as follows:

Subject Transitive verb Article + Quantif. + nominalised verb ...
Sales showed (info) a 6% decrease (info) ...

Note: In this configuration, quantification attaches to the noun instead of the verb. There are two formats for this:

Subject Verb Article Noun Modifier (quantif.) ...
Sales showed a decrease of 6% ...

OR

Subject Verb Article Modifier (quantif.) Noun ...
Sales showed a 6% decrease ...

With the Shorthand Format, there are four potential formats. That is because 'year-on-year', 'month-on-month', etc. can be used either as a sentence adverb or as a modifier to the noun.

'Year-on-year' as a sentence adverb:

Subject Verb Article, noun and quantif. Sentence adverb
Sales showed a 6% decrease
a decrease of 6%
year-on-year

'Year-on-year' as a modifier to the noun:

Subject Verb Article, noun, quantif., and comparison
Sales showed a 6% year-on-year decrease
a year-on-year decrease of 6%

Apart from verb-noun combinations, nominalisations are widely used for various other purposes in English. One is shown in the 'absolute phrase' structure illustrated below.

Causation

All examples so far use intransitive verbs. However, it's also possible to use transitive verbs in a causative sense. For example:

This increased sales (by) 6% compared with the previous month.

This pushed sales up (by) 6% compared with the previous month.

In this sentence, 'this' is the subject (indicating a cause or causative factor), 'to push up/ increase' are transitive verbs, and 'sales' (the metric) is the object. This structure can be used to indicate the cause or factors behind a change.

Absolute phrase or clause

There is a particular stylistic construction, often called an 'absolute phrase', that is heavily favoured in modern English prose. It involves setting a phrase or clause off from the sentence as a kind of comment or amplification. While the stylistic effect is quite conspicuous, linguistically it is less easy to characterise.

Expressions of comparison commonly feature this kind of structure. In the following examples, they function as an explanation or elaboration of the main clause:

Sales in June were 6 million dollars, up 6% over the previous month.

Sales in June were 6 million dollars, an increase of 6% compared with the previous month.

In the first example a preposition is used adverbially. The second uses a nominalisation of the verb 'to increase'.

Observations

Several features stand out in the way that English handles the comparison of current data with earlier data:

1) Methods of abbreviation are notable for their variety, giving the impression of a series of independent patches contrived to fix the wordiness of the Standard Pattern. There is a certain amount of competition among methods, partly geographical in nature (some tend to be more favoured in North America), partly based on the audience (the Shorthand Format, in particular, tends to be associated with the jargon of economic reporting).

2) While it is certainly possible to use formal expressions in making data comparisons, there is a discernible tendency towards informality. One of the main factors behind this is the use of prepositions.

Prepositions in English are complex both semantically and grammatically. They are not confined to positions in front of nouns; they can also be used as adverbs, or as particles in so-called 'phrasal verbs' (e.g. 'to take on').

This variety of functions is widely exploited in expressing comparison over time. Prepositions can be used adverbially to indicate the direction of change, as in the adverbial use of 'down' in:

Sales were down 6%.

They are also used to indicate the relationship between the current period and the period of comparison, as in:

Sales in June declined 6% on the previous month.

This is related in only a very abstract way to the simple preposition 'on'.

Interestingly, the shortest English-language format, the Shorthand Format (e.g. 'year-on-year'), is based on the use of prepositions.

4) English prose has a strong tendency seek variety and flexibility in order to avoid monotony. This can sometimes take the form of variation for variation's sake, as seen in ways of describing the direction and nature of change, especially the 'colourful' verbs of journalistic prose. Writers also try to smooth out clumsy repeating expressions. For instance, the period of comparison may be omitted if it is understood. The purpose of both is to make prose seem less mechanical and more flexible and lively.

5) Comparisons of data are deeply integrated into the structure of the sentence. Even relatively standardised formats share in the same grammatical flexibility as any other structure in English. They are involved in the same word order variations, the same flexibility in use of transitive verbs, the same use of passive constructions, and the same preference for using nominalisations. They are heavily used as 'absolute phrases', a favoured structure in English prose.

While the above characteristics may seem unremarkable as far as English is concerned, they stand in stark contrast to usage in Chinese, and particularly in Japanese.

INTRANSITIVE VERBS

◆ A range of intransitive verbs can fill this slot. Typical examples are:

To express an increase: to rise, to increase, to expand, to grow, to go up, to pick up, etc.

To express a decrease: to fall, to decrease, to decline, to contract, to go down, to plummet, etc.

Of these:

◆ 'Increase', 'expand', 'rise', 'decrease', 'contract', 'decline' etc. are neutral in tone and are appropriate in more formal English;

◆ 'Go up' and 'go down' tend to be encountered in spoken English;

◆ 'Soar', 'jump', 'climb', 'slump', etc. are more often found in journalistic English.

PREPOSITIONS or ADVERBS

◆ Prepositions (or adverbs) like 'up' and 'down' are snappy but somewhat colloquial. The main ones are:

Increase: to be up.

Decrease: to be down, to be off.

◆ 'Up' and 'down' are directly related to phrasal verbs like 'to go up', 'to tick up', 'to edge down', etc.

Possible verbs include to show, to exhibit, to experience, to see, to record, to register, etc. More rarely, verbs such as to achieve and to enjoy may be used in a positive sense (usually an increase) and to suffer in a negative sense (usually a decrease).

Sales showed a 6% decrease.

Sales saw a 6% decrease.

Sales suffered a 6% decrease.

Nominalised forms include an increase, a rise, growth (non-countable), a decrease, a decline, a contraction, a drop, a fall, etc. Nouns like a growth rate may also be used.

In English, the common periods of comparison with the preceding period are:

(1)
the previous month
the prior month
the preceding month

(2)
the previous quarter
the prior quarter
the preceding quarter

(3)
the previous quarter
the prior quarter
the preceding quarter

(4)
the previous half year
the prior half year
the preceding half year

Of these, ‘previous’ is probably the most popular, followed by ‘prior’, then ‘preceding’.

◆ In English, the common periods of comparison with the corresponding period of the previous year are as follows:

(5)
the corresponding / same month of the previous year
the corresponding / same month of the prior year
the corresponding / same month of the preceding year

(6)
the corresponding / same quarter of the previous year
the corresponding / same quarter of the prior year
the corresponding / same quarter of the preceding year

(7)
the corresponding / same period of the previous year
the corresponding / same period of the prior year
the corresponding / same period of the preceding year

Of these, ‘previous’ is probably the most popular, followed by ‘prior’, then ‘preceding’.

◆ English generally uses 'the previous year' in preference to 'last year', even where the 'previous year’ is, in fact, 'last year'.

CONDENSED FORMAT

Condensed formats like the following are often favoured in American business and journalism:

For (5): the prior year’s month / previous year’s month / year-ago month
For (6): the prior-year quarter / previous-year quarter / year-ago quarter
For (7): the prior-year period / previous-year period / year-ago period

For example:

Sales fell by 6% compared with the year-ago quarter.

Sales fell 6% compared with the prior-year quarter.

UNDERSPECIFICATION

The time period may be underspecified if obvious from the context. For example:

Hydropower output in the first four months of 2013 expanded by 6 percent from a year earlier.

Here, the period is the 'first four months of the previous year', but the writer simply refers to 'a year earlier'. The specific period is understood from the context.

Sometimes expressions like 'the previous year's levels' are found.

PARTICIPIAL CLAUSE

◆ The participial clause uses the past participle of the verb ‘compare’ (i.e. 'compared').

◆ The participle is passive in meaning:

House prices fell by 6% when [they are] compared with the previous month.

◆ 'As compared with' is also found:

House prices fell by 6% as compared with the previous month.

◆ Theoretically with is the correct preposition. Compared to should only be used in the sense of 'likened to' (as in 'Shall I compare thee to a summer's day?').

However, 'compared to' is so widely used that many people are probably unaware of any difference.

PREPOSITIONAL PHRASE

It's very common to condense the comparison into a preposition:

Sales decreased 6% over the previous month.

The relationship with the previous period is expressed by the prepositions on, over, from or (less commonly) against.

FANCIER FORMS

Besides simple prepositions, English can also use more elaborate expressions such as relative to (fairly common), versus (uncommon), and vis-à-vis (fairly rare).

Sales decreased (by) 6% relative to the preceding quarter.

FULL Shorthand Format

Under the Shorthand Format, the six periods of comparison are:

(1) month-on-month / month-over-month / month-to-month
(2) quarter-on-quarter / quarter-over-quarter / quarter-to-quarter
(3) year-on-year / year-over-year / year-to-year
(4) year-on-year / year-over-year / year-to-year
(5) year-on-year / year-over-year / year-to-year
(6) year-on-year / year-over-year / year-to-year

Some examples:

Exports declined 6% year-on-year.

Revenue from online games alone climbed 6 per cent quarter on quarter.

ABBREVIATED Shorthand Format

The Abbreviated Shorthand Format can largely be used in the same context as the full Shorthand Format:

The economy grew 6% on-year.

Higher and lower can't be used with all comparison indicators (see below). They can be used with 'compared with', 'in comparison with', 'relative to', 'vis-à-vis', etc., but not simple prepositions (e.g. 'lower on the previous year').

◆ 'Than’ acts as the comparison indicator:

Sales were 6% lower than the same month of the previous year.

◆ Quantification (in this case '6%') usually comes before the adjective, with no use of 'by'.

Sales were 6% lower.

In other positions 'by' must be used:

Sales were lower than the same month of the previous year by 6%.

◆ 'Than the previous month' is frozen in position; it can not be moved to the start of the sentence.

SIX TIME PERIODS

The six common time periods are:

(1) the previous month

(2) the previous quarter

(3) the previous year

(4) the corresponding month of the previous year

(5) the corresponding quarter of the previous year

(6) the corresponding period of the previous year

Needless to say, other time periods are also used, notably 'year-to-date', 'half year', and 'first xx months of the year'.

CONCRETE MENTION

It's not uncommon in English to spell out the specific time period. For instance:

May (preceding month)

the second quarter

the first half

CONCRETE MENTION

It's not uncommon in English to spell out the specific time period. For instance:

June of 20xx (corresponding month of the previous year)

the same month in 20xx (corresponding month of the previous year)

This may be abbreviated in various ways, especially in the media, e.g.

last June (same month of the preceding year)

20xx (same period of the preceding year)

a) Metric being compared -- 'Sales' (or more strictly speaking 'value of sales').
b) Current period -- 'in June'.
c) Expression of change (including direction of change, etc.) -- 'decreased'.
d) Quantification of the change -- ‘(by) 6%’.
e) ‘Comparison indicator’ -- ‘compared with’.
f) The period of time used as the standard of comparison -- 'the same month of the previous year'.

Attaching prepositional phrases to nouns ('sales in June', 'people in America' etc.) is the usual construction in English. However, in some styles (especially media-influenced English), it's not uncommon to find 'June sales' instead.

Also found are expanded expressions like at a rate of 6%.

PART OF SPEECH OF 'UP' AND 'DOWN'

Assignment of 'up' and 'down' to parts of speech is not always consistent.

In 'He sat up', 'up' is an adverb, although some would call it a 'particle'.

In 'He is up', 'up' is variously treated as an adverb or adjective.

In 'He went up the river, 'up' is treated as a preposition.

These are all closely related uses and dividing them according to traditional parts of speech is rather artificial.

For instance, in 'Prices were 6% up', 'up' can't be replaced by an ordinary adjective (like 'high') or adverb (like 'quickly'). 'Up' and 'down' occupy their own niche and are not like the words they supposedly share the same 'part of speech' with.

'LOWER, HIGHER'

Comparative adjectives are more commonly used with 'than'.

Sales in June were 6% lower than the previous year

Constructions using comparative adjectives cannot use prepositions such as 'on' or 'over' to indicate comparisons. That is, it's not possible to say:

Sales in June were 6% lower on the previous year

PASSIVE

In English, the passive is a very common way of focussing attention on the action or event and away from its agent. Although overuse of the passive is rightly maligned by stylistic authorities, the passive (more exactly, the past participle) is the right construction for this occasion.