Chapter 11: Dependent Samples T-Tests

Question 1

If the confidence interval contains 0

Answer 1

then it is not a significant effect

Question 2

If the interval doesn’t contain 0

Answer 2

then the treatment effect was significant

Question 3

assumptions for an independent t-test

Answer 3

1. Observations from each sample are independent
2. The two populations the samples come from must have a normally distributed dependent variable
3. The two populations the samples come from must have equal variances of the dependent variable
   Called the homogeneity of variance assumption

Question 4

homogeneity of variance assumption

Answer 4

The two populations the samples come from must have equal variances of the dependent variable

Question 5

what is the goal of hartley’s f max test?

Answer 5

Test for homogeneity of variance assumption

Question 6

interpreting hartley’s f max values

Answer 6

Small value (near 1.00) indicates similar sample variances

Question 7

f-max formula

Answer 7

f-max= larger variance/ smaller variance

Question 8

what information do you need to calculate f-max?

Answer 8

Alpha level
K (how many samples you have)
Df for each sample variance

Question 9

what if you don’t meet the homogeneity of variance assumption?

Answer 9

you can use a different method to compute the variance and associated standard error (which a computer will do for you!)

Question 10

when to use dependent t-tests?

Answer 10

Used when you have two scores for one participant

Question 11

matching-subjects design

Answer 11

Each individual in one treatment is matched one-to-one with a corresponding individual in the second treatment

Question 12

difference score

Answer 12

D= X₂- X₁
where X₁ is the person’s score in the first treatment, X₂ is the person’s score in the second treatment

Question 13

null hypothesis for a dependent t-test

Answer 13

H₀: μ= 0
States that the population of difference scores has a mean of zero

Question 14

alternative hypothesis for a dependent t-test

Answer 14

H₁: μ≠ 0
States that there is a systematic difference between treatments that causes the difference scores to be consistently positive (or negative) and produces a non-zero mean difference between the treatments

Question 15

df for dependent t-test

Answer 15

n-1

Question 16

dependent t-test formula

Answer 16

t= M-μ/ Sm

Question 17

estimated standard error for dependent t-test formula

Answer 17

Sm= s/√n

Question 18

the dependent t-test is

Answer 18

the same procedurally as the one-sample t-test

Question 19

advantages of dependent t-test

Answer 19

• less variability
• more statistical power

Question 20

disadvantages of dependent t-tests

Answer 20

• Sometimes, people stop showing up for the study, decreasing your sample size
• Order can influence the results of a study

Question 21

measures of effect size for dependent t-tests

Answer 21

cohen’s d & variance explained
same formulas as for a regular one sample t-test

Question 22

confidence intervals for dependent sample t-tests

Answer 22

μD= MD +/- t Smd

Question 23

assumptions for a dependent t-test

Answer 23

• Observations within each treatment condition must be independent
• Population distribution of difference scores (D values) must be normally distributed