T Test (Single Sample And Dependent Means) Flashcards
Why can’t a z test be used to test significance in this situation?
Because there isn’t a population measure of variability (sd or variance)
What do u do when u don’t have a population measure of variability
U must estimate the population variance from the sample variance
What does the t distribution do that the Z distribution doesn’t
It changes according to the sample size
Why do we divide ss by n-1 instead of just n
Because samples will always be smaller than the population and there cause underestimation of the variability in the population. This counteracts that
What is S2
Estimate of the population variance from sample data
What is the n-1 quantity called
Degrees of freedom
What does df represent
The number of scores in a sample that are free to vary when the population mean is estimated
What is Sm
Standard error of the mean
What do u do if ur exact df value is not on the table
Use the nearest one that is less than urs (this gives less chance of making a type 1 error)
What is a dependent means t test
A test that is used to compare each individuals score before and after and intervention
What do we assume the population mean to be in a dependent mean t test
0
What differentiates a single sample t test to a dependent means t test
A dependent means t test uses difference scores and there is assumed population mean of 0
In which situations do you use a tea test for dependent means?
Repeated measures design
Match pairs design
What is a matched pairs design?
Pairs of participants are matched in terms of key variables such as age and IQ. One member of each pair is then placed into the experimental group and the other member into the control group.
What is S
Estimated population sd
