Independent t Tests Flashcards
When are they used
Between subjects design
Where parametric subjects are met
What parametric assumptions need to be met?
- DV is interval or ratio
- IV is categorical
- Normal distribution of DV on each level of IV
- Homogeneity of variance
- No outliers
Homogeneity of variance -
What test?
Probability?
Levene’s test
P > .05 is good - variance doesn’t differ across groups
What 3 things does the t test take into account?
- Size of sample (bigger = better)
- How great the difference is between the 2 means you are comparing
- The standard deviations of the data within your 2 samples
What are the parameters for ‘t’
Mean
Standard deviation
When should an independent samples t test be used
Comparing means for 2 groups
What is the total degrees of freedom
No. Data points - no. Groups
Standard APA format
t (degrees of freedom) = value of t, p =
Presenting the results
(M = , SD = ) twice cos comparing the results then
t ( ) = , p = , two/ one tailed
What does a t test do?
Assesses whether the means of 2 groups are statistically different from eachother