Transcript Document 7753105

Problems of Tutorial 7
1. (4.5, page 116). Name one or more graphs that can be used to validate each of the
following assumptions. For each graph, sketch an example where the corresponding assumption
is valid and an example where the assumption is clearly invalid.
a). There is a linear relationship between the response and predictor variables.
b). The observations are independent of each other.
c). The error terms have constant variance.
d). The error terms are uncorrelated.
e). The error terms are normally distributed.
f). The observations are equally influential on least squares results.
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2. a). Draw a dot-plot for the following data: 23, 24, 35,36,45,100.
b). Draw a stem-and-leaf plot for the data: 1.2,1.3,2.5,2.7,3.3,2.9,3.5.
3. Draw a matrix plot to indicate a data set with response variable Y,
predictor variables X1, X2, X3 and X4. Y and X1, X2, X3 are
positively linearly related, Y and X4 are nearly linearly uncorrelated.
X1 and X2 are collinear, X1 and X3, X4 are linearly uncorrelated, X2
and X3, X2 and X4 are negatively linearly related. There is a
nonlinear relationship between X3 and X4.
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