Advanced Statistics - Exam 2
The results of one-way repeated-measures ANOVA with four levels on the independent variable revealed a significance value for Mauchly's test of p =. 0.048. What does this mean?
The assumption of sphericity has been violated.
Which of the following statements about the F-ratio is true?
The F-ratio is the ratio of variance explained by the model to the error in the model
Which of the following sentences best describes a covariate?
A variable that shares some of the variance of another variable in which the researcher is interested.
If you use a paired samples t-test:
All of these answers are correct
A psychologist was interested in whether the amount of news people watch (minutes per day) predicts how depressed they are (from 0 = not depressed to 7 = very depressed). What does the standardized beta tell us in the output?
As news exposure increases by 1 standard deviation, depression decreases by 0.224 of a standard deviation.
Which of the following statements about the t-distribution is correct?
As the degrees of freedom increase, the distribution becomes closer to normal
Imagine we conduct a one-way independent ANOVA with four levels on our independent variable and obtain a significant result. Given that we had equal sample sizes, we did not make and predictions about which groups would different before the experiment and we want guaranteed control over the Type 1 error rate, which would be the best test to investigate which groups differ?
Bonferroni
Departures from sphericity can be measured using:
Both of the estimates (Mauchly's Test & )
An independent t-test is used to test for:
Difference between means of groups containing different entities when the sampling distribution is normal, the groups have equal variances and data are at least interval.
A paired-samples t-test is used to test for:
Differences between means of groups containing the same entities when the sampling distribution is normally distributed, and the data have equal variances and are at least interval.
When entering data for a repeated-measures design in SPSS:
Each row of the data editor should represent data from one entity, while each column represents a level of a variable.
When the between-groups variance is a lot larger than the within-groups variance, the F-value ___ and the likelihood of such a result occurring because of sampling error is __
Large; low
Imagine we were interested in the effect of supporters singing on the number of goals scored by soccer teams. We took 10 groups of supports of 10 different soccer teams and asked them to attend three home games, one at which they were instructed to sing in support of their team (e.g., 'Come on, you Reds!), one at which they were instructed to sing negative songs towards the opposition (e.g., 'You're getting sacked in the morning!') and one at which they were instructed to sit quietly. The order of chanting was counterbalanced across groups. Which of the following could be used to analyze these data?
One-way repeated-measures ANOVA
A researcher measures a group of people's physiological reactions while watching horror films and compared them to when watching comedy films. The resulting data were normally distributed. What test should be used to analyze the data?
Paired-samples (dependent or related) t-test.
After an ANOVA you need more analysis to find out which groups differ. When you did not generate specific hypotheses before the experiment uses:
Post hoc tests
Imagine we wanted to investigate the effects of three different conflict styles (avoiding, compromising and competing) on relationship satisfaction, but we discover that relationship satisfaction is known to be affected by self-esteem. Which of the following variable would be the covariate in this study?
Self-esteem
Imagine we wanted to investigate the effects of three different conflict styles (avoiding, compromising and competing) relationship satisfaction. We discover that relationship satisfaction is known to covary with self-esteem, so we conduct an ANCOVA with self-esteem as the covariate. What could be a potential issue with this study?
Self-esteem might also be related to conflict style.
Which of the following regarding the assumption of sphericity is false?
Sphericity does not affect post hoc tests
When conducting a one-way independent ANOVA with three levels on the independent variable, an F-ratio that is large enough to be statistically significant tells us:
That one or more of the differences between means is statistically significant but not where the differences between groups lie.
What is multicollinearity?
When predictor variable correlate very highly with each other
Imagine we wanted to investigate the effects of three different conflict styles (avoiding, compromising and competing) on relationship satisfaction, but we discover that relationship satisfaction is known to covary with self-esteem. Which of the following questions would be appropriate for the analysis?
a.What would the mean relationship satisfaction be for the three conflict style groups, if their levels of self-esteem were held constant?
Which of the following is not a reason why multicollinearity a problem in regression?
It leads to unstable regression coeefficients
Which of the following best describes how many covariates can be included in an ANCOVA?
It is a good idea to keep the number of covariates to a minimum.
Which of the following sentences is an accurate description of the standard error?
It is the standard deviation of the sampling distribution of a statistic.
Imagine I ran a one-way repeated-measures ANOVA with five levels of the independent variable. The results revealed a Greenhouse-Geisser estimate, =.977, and the Huynh-Feldt estimate, = .999. What do these values tells us about the assumption of sphericity?
The assumption of sphericity is likely to have been met.
When an experimental manipulation is carried out on the same entities, the within-participant variance will be made up of:
The effect of the manipulation and individual differences in performance.
What is the overall effect of an independent variable on a dependent variable known as?
The main effect
R2 is:
The proportion of variation in the outcome accounted for by the predictor variable or variables
Subsequent to obtaining a significant result from an exploratory one-way independent ANOVA, a researcher decided to conduct three t-tests to investigate where the differences between groups lie.
The researcher should accept as statistically significant tests with a probability value of less than 0.016 to avoid making a Type 1 error
If the differences between group means are large enough, then:
The resulting model will be a better fit of the data than the grand mean.
What does the independent t-test test assume?
The sampling distribution is normally distributed.
When conducting an independent t-test, what is the dependent variable?
The scores
Which of the following is not a rule for conducting orthogonal contrasts?
The sum of weights for a comparison should not be zero.
Which of the following statements about the t-statistic in regression is not true?
The t-statistic is equal to the regression coefficient divided by its standard deviation
Which of the following statements is not true?
Tolerance values about 0.2 may indicate multicollinearity in the data.