Research Question: “Are individual differences in
introspective ability reflected in the anatomy of brain regions responsible for
this function?”
The researcher is hypothesizing that introspective ability
may produce (cause) bigger brain, but this an observational research study.
This hypothesis is speculation only. Cannot be proved with this
observational study.
Make
a scatterplot suitable for predicting volume from introspective ability.
What is the squared correlation r?
For
regression inference, we estimate two parameters among others: Intercept
(α), and Slope (β). From the output, what are the estimates of these
parameters?
What
is the equation of the least-squares regression line of volume on
introspective ability?
What
is the confidence interval for the slope of the population regression
line?
What
does the slope tells us about the relationship between introspective
ability and brain volume?
The
slope tells us something different from the correlation coefficient.
Explain the difference.
Checking assumptions underlying regression analysis:
Plot
the standardized residuals against the standardized predicted values. This
is called a residual plot. Any curvilinear pattern in the distribution of
residuals?
Create
a histogram of residuals. Is there any evidence that the residuals are not
normally distributed?
Are
the observations (rows) in the data set view independent? Explain.
Any
indication of heteroscedasticity, or distribution of residuals get bigger
or smaller at each of the predicted values?
