Independent t-test

This lesson is called Independent t-test, part of the Inferential Statistics with R course. This lesson is called Independent t-test, part of the Inferential Statistics with R course.

Transcript

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Your Turn

Perform an independent samples t-test to test whether there is a difference in exam_1 by athlete. Use var.equal = TRUE. Is there a difference? What is the p-value?
Perform an independent samples t-test to test whether there is a difference in act_english by gender. Use var.equal = TRUE. Is there a difference? What is the p-value?

Notice what happens since gender has 3 levels. Try out using the filter() function from dplyr to only check the difference between Female and Male students. Alternatively, check out the page on t_test() to see how to use the comparisons argument to specify the groups to compare.

Learn More

We are using the rstatix package for the t_test() function (and other functions in later lessons). We use this package because it is tidyverse-friendly while some base R functions for inferential statistics are not. If you did want to use the base R equivalent function for a t-test, it is t.test().

Have any questions? Put them below and we will help you out!

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gene trevino • January 26, 2025

Just curious why my output is not in the same format as yours. This is how mine appears.

.y. group1 group2 n1 n2 statistic df p

Thanks

David Keyes Founder • January 27, 2025

We'd have to see your exact code to be able to give you an answer.

gene trevino • January 27, 2025

college %>% select(exam_1, exam_2) %>% pivot_longer(cols = everything(), names_to = "exam", values_to = "score") %>% t_test(score ~exam, paired = TRUE)

Thanks, Gene Trevino

David Keyes Founder • January 29, 2025

I believe the difference is because Dana is displaying her output using a table function. The difference is merely aesthetic though – the output is identical to yours.

gene trevino • January 29, 2025

How can I learn about the table function ?

David Keyes Founder • January 29, 2025

These slides are made with the {xaringan} package. You can learn about that in my book. In terms of options to make tables, see this blog post. There are many packages to make tables. I typically recommend {gt} and {flextable}.