What is the difference in meaning between the following two sentences:

Comparison across the groups
Comparison between the groups

In other words when I must use "across" and when I should use "between"

closed as off-topic by anongoodnurse, GoldenGremlin, TrevorD, Drew, tchrist May 22 '16 at 19:36

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  • Can you provide more context? – Andy Schweig May 22 '16 at 18:38
  • @ Andy Schweig. What do you want me to add more than what I had wrote. The questions is clear and I gave examples. Thanks for answering my question! – goro May 22 '16 at 18:43
  • Andy was asking for some indication of what was being compared and/or what type of groups are being referred to: groups of people, groups of data, etc.. Please note that this site states that "is a question and answer site for linguists, etymologists, and serious English language enthusiasts". Your question seems more suited to our sister site English Language Learners. Also, if you want to use this site, you are asked to "include the research you've done". – TrevorD May 22 '16 at 18:50
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    @TrevorD Oh, goody! the CPVPV have showed up in force, unfortunately for a perfectly valid question about the idiomatic difference in preposition usage with the verb to compare (and its derivatives). This doesn't strike me as a question for novices. And please spare us the party line about linguists, etymologists and other "serious" people. – deadrat May 22 '16 at 19:12
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    @deadrat I've no idea what "the CPVPV" are - but OP wouldn't give us any context. You've actually said that "It's difficult to be definitive without the context" - so there's no need for your sarcasm! If OP had bothered to respond - at least politely - to the first request for context, we could have responded appropriately. – TrevorD May 22 '16 at 23:01

It's difficult to be definitive without the context you have in mind. But generally, comparison across implies that some ordering to the groups in question. For example, take the article "Stroke Inpatient Rehabilitation: A Comparison across Age Groups" in Journal of the American Geriatrics Society, Volume 42, Issue 1, pages 39–44, January 1994, which compared three groups of stroke victims, "young" (age less than 65), "young-old" (65-74), and "old" (75 and older). The study was looking for trends base on age, and found that going from the younger to the older groups turned up little difference in 3-month survival, but that the oldest group had the poorest motor function both before and after rehabilitation.

Comparison between groups, on the other hand, implies noting similarities and dissimilarities between pairs of members from the set of groups under consideration. Consider this quote from 1994 Indicator Monitoring -- Labour Force Survey Report (p 11, 1996)

Comparison between age groups show that 66 percent of males and 65 percent of females in the age group 5-9 years had not completed any level of education. Of those who had completed at least grade 7 for both males and females, the highest proportion of 23 percent was in the age group 16-19 years.

This is just a statistical statement about levels of education for various groups of school-age girls and boys, with no indication of trends based on age or sex.

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