PSY-PC Test 3 Review
Which of the following statements provides the correct numerator and denominator degrees of freedom for an ANOVA with 10 participants in each of four groups?
3 and 36 degrees of freedom
In a study with three groups and 13 participants in each group, the sum of squares for the within-groups source of variation is 18. What is the value for the mean square within-groups in this study? Report answer to one decimal place.
0.5
Two sources of variability
between group variability within group variability
Effect Size approaches for dependent samples t tests
cohen's d proportion of explained variance
Two Way ANOVA
hypothesis test used when there are TWO independent variables used to create groups
Chi-Square Test
hypothesis test when the dependent variable is discrete
Assumptions for ANOVA
independent random sampling, normal distributions (robust), homogenity of variance (robust)
k
number of levels
N
number of particpants in entire study (k*n)
Goodness-of-fit Test
one discrete
If the group means are similar, then the variance of the group means will be ___.
small
To compute a dependent samples t-test, a researcher has to know many values. Which of the following is NOT a value that the researcher must know to compute this test?
the number of pairs of scores
n
the number of participants in each level
Step 4: Calculate the Test Statistic (Recall: ). Round answer to two decimal places.
4.47
A researcher computes a one-sample z test in two studies. Both studies used the same alpha level, placed the rejection region in both tails, and measured the same sample mean. The researcher selects a sample of 30 participants in Study 1 and decides to not reject the null hypothesis. She selects a sample of 60 participants in Study 2 and decides to reject the null hypothesis. Is this possible?
Yes, the different decisions in Study 1 and Study 2 are possible because the second test was associated with greater power to detect an effect
Homogeneity of variance is an assumption for the one-way between-subjects ANOVA. What does this assumption mean?
that the variance is equal in each population from which samples are selected
Test for independence
two variables
ANOVA
used to determine if differences exist between two or more populations
dependent samples t-test
difference between two related means DV: continuous 1 Discrete IV with 2 means
A researcher conducts a study in which k = 5 and N = 80. What are the degrees of freedom between-groups for the one-way ANOVA?
4
commonly used effect size for ANOVA
proportion of variance
For dependent samples t tests, when do you reject based on a CI
reject null if 0 is NOT in the CI
A researcher compares the difference in the amount of texting by students in class during the first week and last week of classes. The type of design described here is called a
repeated measures design
A researcher is planning a study and expects an effect size of d = .3. What will the power be if she recruits 60 participants?
0.63
Assumptions for dependent samples t test
1. Normality 2. Independence
A researcher is planning a study and expects an effect size of d = .3. How many participants does she need to recruit to obtain a power of .85?
100.0
There are ____ cells or groups in a 3 X 4 ANOVA design
12
A 2 X 3 chi-square test for independence has ___ degrees of freedom?
2
There are ____ factors in a 2 X 3 ANOVA design.
2
What is the minimum number of groups that can be observed using the one-way between-subjects ANOVA design?
2
Chi-square statistic
A measure of the overall difference between observed frequencies and expected frequencies
A two-way ANOVA is a statistical procedure used to test hypotheses concerning the variance of two group means for the levels of one factor.
False
Post hoc tests are conducted following a significant one-way between-subjects ANOVA, only when k > 2.
False
The degrees of freedom for the dependent samples t-test is always the total sample size minus one.
False
A researcher computes a chi-square test for independence and estimates the following effect size: phi = 0.56. This effect size is
Strong
A researcher conducts two studies. Each study was a one-sample z test. Both studies placed the rejection region in both tails and measured the same sample mean. The alpha level in Study 1 was larger than the alpha level used in Study 2. Which study is associated with greater power to detect an effect?
Study 1
A researcher notes that the variability attributed to difference between group means is quite large. Which source of variation is the researcher referring to?
between-groups
Using a two-way ANOVA with Factor A and Factor B, a researcher found that scores for Factor A varied across the levels of Factor B. In this study, the researcher found a significant
interaction
Using a two-way ANOVA, a researcher concludes that Factor A is significant, independent of Factor B. In this study, this researcher found a significant
main effect of Factor A
A researcher asks a sample of brothers and sisters to rate how positive their family environment was during childhood. In this study, the differences in ratings between each brother and sister pair were compared. The type of design described here is called a
matched samples design
odds
numerical expression of the likelihood that an event of interest will occur
The term "between-subjects" refers to
observing different participants one time in each group
post hoc tests
pairewise comparison made after finding that F is significant (in other words, we have rejected null)
All other things being equal, as the degrees of freedom increase, what happens to the critical value for a dependent samples t-test (or for any t-test, for that matter)?
The critical value increases
A mean square is a sample variance.
True
The test statistic formula is the same for a chi-square goodness-of-fit test and a chi-square test for independence.
True
