A researcher uses a repeated-measures design to compare individuals' performance before treatment with their performance after treatment. If all of the participants show improved performance of 8 or 9 points after treatment, what should the researcher find?
The variance of the difference scores is near zero.
A researcher uses a repeated-measures study to compare two treatment conditions with a set of 20 scores in each treatment. What would be the value of df for the repeated-measures t statistic?
df=19
A sample has a mean of M = 39.5 and a standard deviation of s = 4.3, and produces a t statistic of
t = 2.14. For a two-tailed hypothesis test with α = .05, what is the correct statistical decision for this sample?
It is impossible to make a decision about H0 without more information.
A sample is selected from a population with μ = 46, and a treatment is administered to the sample. After treatment, the sample mean is M = 48 with a sample variance of s 2 = 16. Based on
this information, what is the value of Cohen's d ?
d=0.50
A sample is selected from a population with μ = 46, and a treatment is administered to the sample. After treatment, the sample mean is M = 48 with a sample variance of s2 = 16. Based on this information, what is the value of Cohen's d?
d=0.50
A sample is selected from a population with μ = 70, and a treatment is administered to the sample. After treatment, the sample mean is M = 74, and Cohen's d is d = 1.00. What is the value
of the sample variance?
s2 = 16
A sample is selected from a population with μ = 70, and a treatment is administered to the sample. After treatment, the sample mean is M = 74, and Cohen's d is d = 1.00. What is the value
of the sample variance?
s2=16
A sample of n = 4 scores has SS = 60. What is the variance for this sample?
20
A sample of n = 4 scores with SS = 48 has a variance of s2 = 16 and an estimated standard error of 2.
True
A sample of n = 9 scores has a variance of s2 = 36. What is the estimated standard error for the sample mean? 2
Although a repeated-measures study measures two scores for each participant, the sample mean and variance are computed using only one score for each participant.
True
An independent-measures research study uses a total of 18 participants to compare two treatment
conditions. If the results are used to construct a 90% confidence interval for the population mean difference, then the t values will be ±1.746.
True
An independent-measures study produces t(10) = 3.00, p < .05. For this study, if effect size is measured with r2, then r2 = 3/13.
False
As the sample size is increased, the distribution of t statistics becomes flatter and more spread out.
False
Compared to a z-score, a hypothesis test with a t statistic requires less information from the population.
True
Confidence intervals with the independent-measures t statistic are used to estimate how much difference there is between two population means.
True
For a repeated-measures study comparing two treatment conditions, a researcher obtains a sample of n = 9 difference scores with a mean of MD = 4 and a variance of s2 = 36. What is the value for the repeated-measures t statistic for these data?
4/2
