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NBME 22 Answers

nbme22/Block 3/Question#22 (reveal difficulty score)
A study is conducted to assess the prevalence ...
Chi-square test ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–

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 +25  upvote downvote
submitted by โˆ—usmleuser007(462)

Just remember:

1) T-test (tea for two) = looks at the mean values of 2 groups

2) ANOVA (analysis of variance) ~ like t-test but = looks at mean values of 3 or more groups

3) Chi-square = looks at the (%) or proportions between 2 or more groups.

so, just look for how many groups being addressed and what values they are using (% or means)

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 +21  upvote downvote
submitted by โˆ—mcl(670)

Despite a numeric value (blood pressure) being measured, patients would be designated either hypertensive or normotensive. To my understanding, the best test for comparing categorical variables across groups is a chi square test.

In contrast, a t-test is used to compare between the means of two groups (measured variable must be quantitative).

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 +2  upvote downvote
submitted by โˆ—d_holles(218)

I was never taught what t-test vs Chi-squared was. Going off of the FA table didn't help. This video below explained the concept really well.

For the Q refer to @mc1's comment.

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 +0  upvote downvote
submitted by โˆ—usmleuser007(462)

1) Analysis of variance is a procedure used for comparing sample means to see if there is sufficient evidence to infer that the means of the corresponding population distributions also differ.

2) Where t-test compare only two distributions, analysis of variance is able to compare many. โ€ข What does the one-way part mean? It is one dependent variable (always continuous) and exactly one independent variable (always categorical). A single independent variable can have many levels.

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 +0  upvote downvote
submitted by medstudied(0)

Why is the correct answer chi-square test? I get that itโ€™s used for categorical variables but weโ€™re comparing prevalence percentages. Is that considered categorical?

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liverdietrying  Youโ€™re looking at two categorical variables, Caucasian vs. AA and HTN versus normotensive. So youโ€™re still using Chi2 to analyze. +8

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