T-statistics Flashcards
1
Q
What are t-tests?
A
Compares the means of two groups on a given variable
- Related t-test
- Independent samples t-test
2
Q
Related t-test
A
- Two groups, paired with each other
With themselves (two different times) or a partner - To reduce error in the outcome variable
- Compare the means between the groups; is there a difference and is the difference significant?
- Compare obtained t-value against the maximum we would expect to get if null hypotheseis were true
- Critical t-value
3
Q
Related t-test - Example
A
- 10 couples
- Measuring marriage satisfaction
4
Q
Related t-test - APA style
A
- t-value (n-1); x,yz, p<=> 0.05
5
Q
Related t-test - Tables of interesst
A
- Paired samles statistics
Mean, N, SD - Paired Difference Test
Mean of difference, SD of difference scores, confidence interval , last 3 columns check if the test is significant or not
6
Q
Independent t-test - When to use it
A
- Compare means of two independent groups
Males vs Females
Control vs Experimental
Students different countries
Not related to each other - One given variable
7
Q
Independent t-test - Example
A
- Sweden participants vs Norway participants
- Immigrants making a country better or worse
8
Q
Independent t-test - Tables of Interest SPSS
A
- Group statistics
Mean scores - Independent test (Table 2)
First two columns; Homogeneity of varience
The 3 columns after; whether the test is significant or not
9
Q
Independent t-test - APA style
A
- Look at t-value, N value, p-value, M in different groups, SD and Cohen’s d.
10
Q
Cohen-s d Values
A
- Small effect .2
- Medium effect .5
- Large effect .8
11
Q
What is confidence interval?
A
If mean of difference is between the confidence interval, it means that the difference i s plausible
