Test Questions Flashcards
The linear regression model is also called the OLS regression because:
It is based on the smallest sum of squared errors between the regression line and the raw data.
In logistic regression, to see if the predictor in the regression model is better than the y-intercept only in the regression model, the:
Null deviance should be greater than the Residual deviance.
In a randomized control experiment for severe depression, there are 2 groups: psychotherapy versus waitlist control. Those in the waitlist control group got less depressed from baseline to the end of the treatment period. One explanation for this is:
Regression to the mean.
The logistic regression uses a statistical method to create a predictive model that makes the sample data most likely to occur or be predicted. This method is called the:
Maximum likelihood method.
Random intercept
Paired with coefficient (u0), it represents cluster-level deviations from the population average.
Fixed Slope
The population average of the effect of the predictor on Y-hat.
Random Slope
Paired with coefficient (u1) it allows for deviations from the population average.
Fixed Intercept
The population average of the y-intercept effect.
Table: Simple slopes of PHQ and gaming on post-gaming mood.
What is the outcome variable?
Post-gaming mood.
Table: Simple slopes of PHQ and gaming on post-gaming mood.
How would you define the depression variable as used in this study?
A continuous moderator.
Level
A component of a data hierarchy. Level 1 is the lowest level, for example, students within schools or repeated measurement occasions within individual subjects.
Cluster
A grouping containing ‘lower level’ elements. For example, in a sample survey the set of households in the neighborhood.
Nesting
The clustering of units into a hierarchy.
Random part
That part of a model that is the contribution of the random variables at each level.
Change in depression will be significantly greater for those in the CBT group compared to the WLC group
OLS Regression with a dummy code for treatment. WLC is the reference group.
Either treatment (i.e., CBT or DBT) increase the odds of finding a job after leaving the inpatient care center compared to WLC.
Logistic regression with a WLC reference group.
Depression will vary across the 10 clinics, and rate of change will likely vary by clinics across levels of treatment (CDT, DBT, WLC) with respect to depression at time 1 vs. time 3.
Mixed effect model with a random intercept, WLC is the reference group for the random slope of treatment.
Quality of life based on a 10-question measure with a 7-point likert scale.
Interval
Number of days
Ratio
Type of anxiety disorder (GAD, Social anxiety, Specific phobia)
Nominal
Symptom severity (mild, moderate, severe)
Ordinal
Fixed Effects
This reflects the group average y-intercept and regression coefficient (slope).
Level 2 (Person) Random Effects
This reflects predictors based on individual y-intercepts and slopes.
Level 1 (Occasion) Random Effects
This reflects the error or deviation of the individual subjects’ raw scores from the predicted y-scores.
In MEM, to determine if studying alone will lead to more improved test scores over time than studying in small groups, which effect or term should be significant?
The interaction of study type and time must be significant.
When doing group comparisons for each time point of a longitudinal study, the research must worry about:
Experimentwise Type I error.
Order from first to last:
- Center variables
- Check for interaction
- Run multiple regression
- Interpret post-hoc tests
- Center variables
- Run multiple regression
- Check for interaction
- Interpret post-hoc tests
“Results of the model indicated that the odds of a patient who is treated being cured are 3.42 times higher than those of a patient who is not treated.” This result is an example of:
Logistic regression.
Correlation
Fully standardized
Covariance
Scale dependent
Regression coefficient
Partially standardized
Correlation
Scale-invariant
Covariance
Unstandardized
Not fully standardized
- For every three inches in height, openness increase .25 likert scale points.
- Covariance.
- b-weight
- For every 1 unit increase in depression, there is a corresponding 4 unit increase in depression as measured by the BDI.
Fully standardized
- Correlation
- There is a small correlation between X & Y, such that as X increases, Y decreases (r = .18).
- For every standard deviation increase in happiness there is a corresponding .2 standard deviation increase in quality of life.
- beta-weight
SS Regression
variability in Y that can be explained by the predictor, represents the component Y that is shared with X1
SS Residual
variability in Y that cannot be explained by the predictor, simply what is ‘left over’ after accounting for x
Imagine we are looking at depression scores (y) and have IVs of age (x1) and distance from the therapist’s office (x2). We want to evaluate the main effects for age & distance using regression. We wisely decide to center the variables.
Our centered coefficient (bo) is the value of height when the age is _______ and distance from the office is ______.
Average; average.
In multiple regression with continuous independent variables, we need to center the independent variables around the means before we center the interaction variable because…
We want the correlations between the independent variables & interaction to be zero.
In multiple regression, if the correlation between X2 and Y is zero, but when X2 entered into the multiple regression in Step 2, it causes the R squared to increase, this is called:
Supression
A partial correlation will always be larger than the semi-partial correlation because…
The denominator of the partial correlation is smaller.
In dummy coding for a multiple regression, b1 is…
The difference between the mean of the reference group and the mean of another treatment group.
R output.
Look at adjusted R-square value to determine stress predicting depression severity.