Exam 2 - Quantitative Methods in Psychology
The paired t and the within subjects F should be used only when the data are in the form of at least (interval, ordinal, or nominal) ____ data
interval
If the within-group variability is small, then the separate sample groups are most likely to have ___ (platykurtic or leptokurtic) distributions.
leptokurtic
The Pearson R assumes that the association between X and Y is always curvilinear (T/F)
False - assumes that it is linear - curvilinear yields a non significant pearson's r
A five-group research design with six subjects in each group has _______ between degrees of freedom and ________ within degrees of freedom
4, 25
In an experiment, the numerator in the F statistic is a measure of Group of answer choices A. the effect of the independent variable on the dependent variable B. the effect of individual differences among subjects on the dependent variable C. the effect of the dependent variable on the independent variable D. the effect of the number of subjects on the dependent variable
A
The effect size statistic for the 1-way ANOVA is Group of answer choices A. eta-squared B. partial eta squared C. Cohen's d D. the coefficient of determination
A
The term -2r(SEM1)(SEM2) in the paired samples t-test causes the t-ratio to be ________ than it would if the term were excluded. Group of answer choices A. larger B. smaller C. more biased with respect to the population parameter D. less biased with respect to the population parameter
A
The higher the correlation between X and Y, the more information about Y is contained in X (T/F)
True
If the Pearson's r between variables X and Y is -.50, how much of variance in Y can be predicted by X? Group of answer choices A. 50% B. 25% C. none - negative correlations do not permit you to explain variance in a criterion variable D. you cannot tell from the Pearson's r how much variance in Y can be predicted from X.
B
In a one-way ANOVA, as the sum of squares within increases, the probability of accepting the null hypothesis Group of answer choices A. decreases B. increases C. remains constant D. you cannot tell because the degrees of freedom within changes depending on the value of the sum of squares within.
B
With respect to the paired-samples t-test, as the size of the r increases, the t-ratio _____ making it ________ to reject the null hypothesis. Group of answer choices A. increases; less likely B. increases; more likely C. decreases; less likely D. remains the same; equally likely
B
In #24 above, which F values would be most likely to be significant? Group of answer choices A. The F for the effect of age B. The F for the effect of drug C. The F for the interaction D. It is most likely that all 3 F values are significant.
C
The coefficient of determination is equal to _______ and tells us ___________. Group of answer choices A. the SSbetween divided by the SS within, the effect size of F B. the SS between divided by the SS between + SS within; the effect size of F C. r squared; the % of variability in Y accounted for by X D. sqrt of r; the % of variability in Y accounted for by X
C
The effect size statistic for the paired-samples t-test is Group of answer choices A. eta squared B. partial eta squared C. Cohen's d D. the coefficient of determination
C
When both the independent and dependent variables are interval/ratio level, which statistical test should be used? Group of answer choices A. paired-samples t B. independent samples t C. Pearson's r D. either A or C, because the same people (or items) are being measured twice.
C
Which of the following is used in determining the degrees of freedom between in the 1 way ANOVA? Group of answer choices A. the number of independent variables B. the number of subjects or scores C. the number of levels of the IV D. none of the above
C
Why do we conduct a post-hoc test if we find a significant F in a one-way ANOVA? Group of answer choices A. Because the book and Prof. Kilianski told us to. B. Because the sum of squares within underestimates the population sum of squares C. Because you don't know which means differ from which other ones when there are more than two of them. D. Because smaller sample sizes are less likely to yield significant differences, and each group is a smaller sample than the total N.
C
Why is the term 2r(SEM1)(SEM2) not included in the independent samples t-test? Group of answer choices A. Because we only use SEM1 in the independent samples t-test B. Because the relationship in an independent samples t-test is assumed to be non-linear C. Because the r is assumed to be 0 in the independent samples t-test D. Because the denominator in the independent samples t-test underestimates the estimated standard error the difference
C
A study found that, compared to a placebo, a drug intended to reduce hyperactivity in teenagers reduced hyperactivity in those under 15, but increased hyperactivity in those under 15. This result would be described as Group of answer choices A. a main effect for age and a main effect for the drug B. an interaction between the drug and hyperactivity C. an interaction between age and hyperactivity D. an interaction between the drug and age
D
If the F statistic is significant in the 1-way ANOVA, the next step to take would be Group of answer choices A. to report the result and reject the null hypothesis. B. to report the result and accept the null hypothesis C. to accept the null hypothesis and conduct a post-hoc test D. to reject the null hypothesis and conduct a post-hoc test
D
In the paired samples t-test, the value of t tells you how many _______ you are from ______________. Group of answer choices A. estimated std. errors of the mean ; the population mean B. estimated std. errors of the mean ; 0 C. estimated std. errors of the difference; the population mean D. estimated std. errors of the difference ; 0
D
Which of the following, if any, is true with respect to Pearson's r? Group of answer choices A. Either of the variables must be ordinal B. The ranges of values for X and Y can be no greater than + or minus 1 SD of their means. C. The form of the relationship between X and Y can be non-linear D. None of the above are true
D
If sample sizes are equal, the pearson's r and the rs predict with exactly the same degree of accuracy (T/F)
Disregard - for ordinal data
In the F statistic, the sum of squares between is influenced by Group of answer choices A. variation within each group in the design B. differences between each group mean and the grand mean C. the number of groups (or means being compared) in the study D. A and B E. B and C
E
Whenever a correlation is significant, the possibility of a cause-and-effect relationship is totally ruled out (T/F)
False - causality has to do with research methods - not the statistic. There is a possibility of causality when it is significant. If it is experimental then you have evidence for causality.
If the range of either set of sample scores is in any way restricted, the Pearson r will overestimate the degree of correlation. (T/F)
False - it underestimates the correlation and reduces the pearson's r
For an equal number of scores, the paired t has more degrees of freedom than the independent t (T/F)
False - paired t always has smaller number of df because N is for pairs of people and in independent N is the total number or people
The paired t may test only the hypothesis of association, whereas the independent t may test the hypothesis of difference as well.(T/F)
False - paired t is a test of mean differences, r is the test of association
The type-2 error occurs when the null hypothesis is rejected when it should not have been(T/F)
False - that is a type 1 error
The paired t ratio may never be used for making population inferences.(T/F)
False - that is what it is used for and the point of the course using sample data to make population inferences.
When a calculated F ratio has a large value, it indicates that the variability between groups is ___ than the variability within groups.
Larger
The number of visible police cars on a highway, and the number of cars exceeding the speed limit (positive/negative relationship)
Negative
The amount of media news coverage of crime and the public's fear of crime (positive/negative relationship)
Positive
The higher a person's score on the SOGS test of gambling addictions, the more moving-violation citations the person has had (positive/negative relationship)
Positive
the more a person uses illegal drugs, the greater the likelihood of illness and premature death (positive/negative relationship)
Positive
Total variability results from the accumulated differences between each individual score and
Sum of Squares total
Between-group variability results from the accumulated differences between each samle mean and
The grand mean
Significant correlations always predict better than chance (T/F)
True - if it is statistically significant it means the null hypothesis is probably not true, chance is the null hypothesis is true.
For both t and F, whether from correlated or independent designs, the more subjects being tested, the greater is the number of degrees of freedom.(T/F)
True - is usually N - number so if higher N higher df
The higher the Pearson r, the higher is the coefficient of determination (T/F)
True - it is r^2 so the higher the r the higher the square will be.
To use the Pearson r, both sets of paired scores must be composed of at least interval data (T/F)
True - must calculate Z scores and need interval level data for that
The paired t as its ultimate goal the detection of differences between two sets of interval measures when the data sets are correlated. (T/F)
True - need the scores to be correlated because if not the r is 0
When comparing correlations from two separate and unmatched samples, the larger the sample sizes, the higher likelihood of finding a significant difference (T/F)
True - the smaller your N the bigger your Z
the greater the spread among the various sample means, the larger the (between or within) _____ variability
between
When an ANOVA results in the rejection of the null hypothesis, then the ______ variability must be larger then the ________ variability
between group variability, within group variability
The variance, or mean square, results from dividing the sum of squares by
degrees of freedom
In matched-subjects designs, the subjects should be equated on some variable(s) that is(are) related to the (independent or dependent) variable
dependent
A within-subjects F ratio performed on data from a matched subjects design results in a (higher/lower) F ratio than would be obtained by an independent One - Way ANOVA performed on the same data.
disregard
On a factorial ANOVA the interaction effect will always be significant if the mean effects themselves are significant (T/F)
false
On a four-group design, the degrees of freedom for a one-way ANOVA must equal 4 (T/F)
false
When an obtained value of F is larger than the table value F for a given number of df, the null hypothesis cannot be rejected (T/F)
false
the one-way ANOVA demands that at least four sample groups must be compared. (T/F)
false
The fact that paired-t has fewer degrees of freedom than does its independent counterpart, and that fact alone, has what effect on the probability of achieving significance
lower probability of rejecting the null
when all its assumptions are met, the paired t is (more or less able) ____ than the independent t to reject null when only a small difference exists b/w the sample means
more able
Within-group variability results from the accumulated differences between each individual score and
the group mean/sample mean
The total sum of squares is made up of two main components, the ______ and the _______
the sum of squares between and the sum of squares within
ANOVA assumes that the data are at least interval (T/F)
true
An F ratio of 5.00 indicates that the variance between groups is five times greater than the variance within groups. (T/F)
true
The F ratio is a non-directional two-tailed test of differences among sample groups whenever the data are in interval form (T/F)
true
For an independent samples t-test and a paired samples t-test with same number of subjects, the degrees of freedom would be the same. Group of answer choices True False
False
Assuming that the mean differences and standard deviations are constant, you are less likely to reject the null hypothesis when using a paired-samples t-test than an independent samples t-test. Group of answer choices True False
False
In a 1-way ANOVA, if the sum of squares between remains constant and the number of means being compared increases, you are more likely to find a significant difference among the means. Group of answer choices True False
False
With respect to a factorial ANOVA, if both main effects are significant, the interaction must also be significant. Group of answer choices True False
False
Negative correlations, even when significant, never predict better than chance (T/F)
False - It being negative has nothing to do with it pbeing able to predict better than chance - we use the absolute value to see if we reject the null, positive or negative correlations do not show the strength of the correlation.
when calculating the paired t ratio, what effect does a substantial correlation have on the size of the resulting t ratio
It reduces the denominator, so the T becomes larger
Effect size may only be applied to the paired t when the t ratio has been shown to be significant.(T/F)
True
In a 1-way ANOVA, both the number of levels of the independent variable and the size of the sample influence the degrees of freedom within. Group of answer choices True False
True
In a factorial ANOVA, when neither main effect is significant, the interaction may still be significant. Group of answer choices True False
True
The reason there is only one number shown for degrees of freedom in any t-test is because the degrees of freedom between must always be 1. Group of answer choices True False
True
To do a factorial ANOVA, there must be a minimum of at least four different treatment conditions. (T/F)
True
When an ANOVA results in the rejection of the null hypothesis, the between-group variability must be greater than the within-group variability. Group of answer choices True False
True
If the correlation between X and Y is high and the correlation between X and Z is high, then the correlation between Y and Z must be high (T/F)
True - X accounts for a lot of the variability in Y and Z so the shared variability between Y and Z must be high.
A pearson r of .90 means that the percentage of information about Y contained in X is roughly 81% (T/F)
True - exactly 81% it is r^2
The more degrees of freedom a given t ratio has, the higher the likelihood of rejecting the null hypothesis.(T/F)
True - for any t test
The use of the factorial ANOVA is required whenever there is more than one independent variable and the data are in interval form. (T/F)
true
