July 5, 2012

Weekly Language Usage Tips: chi square or chi squared & pick a preposition

Posted in chi square/chi squared at 6:40 am by dlseltzer

This is a short work week due to July 4 holiday, so I thought we would go with a quick and dirty wlut.

Tip 1: chi square or chi squared

A reader writes:

A wlut question: chi square or chi squared?

To provide the reader with a quick answer, I decided to perform a Googlefight.

[NOTE: Googlefight is not affiliated with Google in any way, but if you enter two search terms, it counts the number of mentions of those terms in a Google search. For instance, a Googlefight of the names, Steve Jobs and Mark Zuckerberg, (a Googlefight of the month) showed 597 million hits for Jobs versus a paltry 23 million  hits for Zuckerberg.]

Anyway, first I did a fight between chi square and chi squared, and chi square was the clear winner with seven and a half million hits compared to chi squared’s 364,000 hits. I then added the term, test, to the fight. Chi square test dropped to about 850,000 hits, and chi squared test dropped to about 280,000 hits.

That was fun, but not very scientific, so at this point, I asked the Chair of the Department of Biostatistics, and this is what she told me:

I say chi squared because it literally is the chi squared. Like x squared.

Another senior statistician friend confirmed this. So there it is: Even though chi square is used frequently, chi squared is the proper term.

So keep in mind that while Google searches and Googlefight may be fun, they don’t provide the authoritative answer especially regarding statistical issues.

Tip 2: Choosing the right preposition

A reader writes:

Could you help settle a disagreement? We need a brief way of saying that participants get feedback on/to/from their self-monitoring entries, but we all disagree on what preposition fits best …

Changes in medication compliance were compared between those who received daily feedback ( ? ) self-monitoring of medication compliance and those who did not.

Any suggestions?

Sometimes finding the best word can be challenging. You want to use a word that helps clarify your meaning. I think what it makes it particularly hard, here, is the inclusion of the word, self-monitoring. Participants are getting feedback from a third party source based on the third party’s review of the participant’s record of monitoring his or her own compliance with respect to medications. At least, that us what I assume is being communicated here. If it clear in the manuscript that the review is of self-monitored data, then I would take the word, self-monitoring, out completely; that would make the sentence easier to understand.

But, be that as it may, you asked for my input about this sentence and about these prepositions (on, to, from). So let’s try each of them in the sentence.

Changes in medication compliance were compared between those who received daily feedback on self-monitoring of medication compliance and those who did not.

On‘ works. Try it without the words, self-monitoring of, and see how much better it sounds.

Changes in medication compliance were compared between those who received daily feedback from self-monitoring of medication compliance and those who did not.

For ‘from‘ to work, ‘self-monitoring’ needs to remain (or be replaced with ‘record’ or ‘report’ or something like that). you need to show that the feedback is derived from something that reports on medication compliance.

Changes in medication compliance were compared between those who received daily feedback to self-monitoring of medication compliance and those who did not.

To‘ doesn’t work at all. You can’t receive feedback TO something.

So if these were my only choices, I would go with ‘on’ or ‘from.’ But I would really prefer another choice and think ‘regarding’ makes the meaning clear.

Changes in medication compliance were compared between those who received daily feedback regarding self-monitoring of medication compliance and those who did not.

(And I would also delete ‘self-monitoring of.’)

Changes in medication compliance were compared between those who received daily feedback regarding medication compliance and those who did not.

Better already.

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