Research Methods Y2 - Parametric Tests of Difference Flashcards
What is the purpose of the unrelated t-test?
The unrelated t-test is a test of difference between two sets of data. It is used with interval-level data when an independent groups design is used. It assumes the participants are drawn from a normally distributed sample within the population, and there is homogeneity of variance.
What are the hypotheses in the unrelated t-test example?
Alternative hypothesis: There is a difference in the time taken by males and females to complete a jigsaw puzzle. (non-directional, two-tailed).
Null hypothesis: There is no difference in the time taken by males and females to complete a jigsaw puzzle.
What is the first step in the unrelated t-test?
Calculate the necessary values for Group A (sum 𝑋𝐴) and Group B (sum 𝑋𝐵)
Square each value in sum 𝑋𝐴 and sum𝑋𝐵.
How is the t value calculated in the unrelated t-test?
t = (Xa - Xb)/sqr root of (Sa+Sb/Na+Nb-2) x (Na + Nb/NaNb)
Where Sa = sum of Xasquared - ( Sum of Xa)squared/Na
same with Sb`
What is the critical value in the unrelated t-test?
The critical value for a two-tailed test at the 0.05 level is found in the critical values table.
How do you determine significance in the unrelated t-test?
If the calculated t value is greater than the critical value (ignoring the sign), the null hypothesis is rejected, and the alternative hypothesis is accepted.
What is the purpose of the related t-test?
The related t-test is used when comparing two sets of data from the same participants (repeated measures design). It assumes the data is interval, normally distributed, and there is homogeneity of variance.
What are the hypotheses in the related t-test example?
Alternative hypothesis: There is a reduction in heart rate activity when comparing heart rate before and after cognitive behaviour therapy. (directional, one-tailed).
Null hypothesis: There is no difference in heart rate activity comparing heart rate before and after cognitive behaviour therapy.
What is the first step in the related t-test?
Calculate the difference (d) between the two sets of scores for each participant, then:
Square each difference (𝑑^2).
Add up the values of d and d^2 .
How is the t value calculated in the related t-test?
t = sum of d/square root of (n x sum of d^2) - (sum of d^2)/n -1
What is the critical value in the related t-test?
The critical value for a one-tailed test at the 0.05 level is found in the critical values table.
How do you determine significance in the related t-test?
If the calculated t value is greater than the critical value, the null hypothesis is rejected, and the alternative hypothesis is accepted.
What is a ‘Parametric test’?
A parametric test is a statistical test used when data is interval level and assumes normal distribution.
What does ‘Homogeneity of variance’ mean?
Homogeneity of variance means that the spread of scores is roughly equal in both groups being compared.
What does ‘Interval-level data’ mean?
Interval-level data refers to data measured on a scale of equal units, such as time or temperature, with no true zero point.
