t-test in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a t-test used for in statistics?

A t-test is used to compare the means of two groups to see if they are significantly different from each other.

beginner

What are the two main types of t-tests?

The two main types are: 1) Independent (two-sample) t-test, which compares means from two different groups, and 2) Paired t-test, which compares means from the same group at different times or conditions.

beginner

In R, which function is used to perform a t-test?

The function t.test() is used to perform a t-test in R.

beginner

What does the p-value from a t-test tell you?

The p-value tells you the probability that the observed difference between groups happened by chance. A small p-value (usually less than 0.05) means the difference is statistically significant.

beginner

How do you specify a paired t-test in R using t.test()?

You set the argument paired = TRUE inside t.test() to perform a paired t-test.

Which R function is used to perform a t-test?

A lm()

B t.test()

C summary()

D mean()

The t.test() function is specifically designed to perform t-tests in R.

What does a p-value less than 0.05 usually mean in a t-test?

A The difference between groups is statistically significant

B The sample size is too small

C The test was performed incorrectly

D The difference between groups is likely due to chance

A p-value less than 0.05 usually means the difference is statistically significant, not likely due to chance.

Which argument in t.test() makes it a paired t-test?

A type = 'paired'

B paired = FALSE

C paired = TRUE

D method = 'paired'

Setting paired = TRUE tells R to perform a paired t-test.

An independent t-test compares:

A Means from the same group at two times

B Variances of two groups

C Median values of two groups

D Means from two different groups

An independent t-test compares means from two different groups.

Which assumption is important for a t-test?

A Data should be normally distributed

B Data must be categorical

C Groups must have the same number of observations

D Data must be binary

A key assumption for t-tests is that the data in each group should be approximately normally distributed.

Explain what a t-test is and when you would use it.

Think about checking if two groups are really different or just by chance.

Describe how to perform a paired t-test in R and what it means.

Consider situations like measuring before and after treatment on the same people.