T-test for two samples Flashcards
T-tests
The hypothesis test for determining if there is a difference between the means of two populations.
Why is t used?
To correct for using a sample std to estimate the standard error.
A normal distribution is…
A t-distribution with infinite degrees of freedom.
What are degrees of freedom?
Max number of independent values in the sample.
T-stat is needed when…
Using multiple sample stats to estimate a population parameter.
Z-stat is needed when…
Using one sample stat to estimate a population parameter.
Two samples are paired when they are…
Not independent.
A paired t-test is used when…
The sample stats are dependent.
Example: measures for the same group for two years.
ANOVA is used to…
Know if there are differences between more than two groups.
Why to run a pairwise t-test?
To know which groups have significant difference
