Stat 160 Prequiz over Sections 1.8 and 1.9
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1. Suppose we are interested in predicting the weight (Y) of a person (in lbs) in terms of the height (X) of the person (in inches). A line
Y = a + bX
is fit. The meaning of the slope parameter,
b
, in this case is one of the following.
The slope is the average weight of the sampled people.
The slope is the expected increase in height for a single pound increase in weight.
The slope is the expected increase in weight for an increase of 1 inch in height.
The slope has no practical meaning in this case.
2. Which of the following is true about the Wicoxon fit?
The Wicoxon fit is robust but not as scientific as the eyeball fit.
The Wicoxon fit is robust in the presence of outliers in the Y-direction as compared to the least squares fit.
The Wilcoxon fit does not give estimates of the slope and the intercept.
The Wilcoxon fit is very sensitive to outliers in the Y-direction.
3. A residual is
the difference between the estimated slope and the estimated intercept.
the difference between the maximum and the minimum values of Y.
a mixed drink made of several kinds of rum, liqueur, and fruit juice.
the difference between the measured value of Y and the predicted value of Y.
4. Which of the following is
not
true about residual plots?
The residual plot is the plot of the residuals versus the predicted values of Y.
A random scatter in a residual plot indicates a good model.
The existence of a definite pattern in the residual plot indicates a good model.
An outlier in the Y-direction stands out in a Wilcoxon residual plot.