The book Small Data Sets reports on an article by Kadiyala, Testing for the ­Independence of Regression Disturbances [Econometrica (1970) 38: 97 117]. This article

The book Small Data Sets reports on an article by Kadiyala, €œTesting for the ­Independence of Regression Disturbances€ [Econometrica (1970) 38: 97€“ 117]. This article contains ­information on ice cream consumption over 30 4- week periods from March through July. The ­researchers were interested in determining what explanatory variables impacted the level of ­consumption. The variables considered in the study are
y, ice cream consumption, pints per capita€¦€¦€¦ x1, price of ice cream, $ per pint
x2, weekly family income, $............................................. x3, mean temperature, ° F

a. Fit the model y = β0 + β1x1 + β2x2 + b3x3 + ɛ to the ice cream data. Is there evidence in the residual plots of serial correlation?
b. Perform a Durbin€“ Watson test for serial correlation. Does the test confirm your observations from the residual plots?

as 72 72 67 60 44 40 32 27 28 3 4 5 6 7 82 80 78 84 86 85 87 94 92 95 96 94 96 y asi 70 43 86 42 3 300 24 006 300 39 3% Als Per 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 41 56 63 68 69 65 61 47 32 24 28 26 32 40 55 01 80 76 78 82 79 76 79 82 85 86 83 84 575 y 3% sha 193 $25 006 34 101 38 29 2% 2% 198 220 123456789012345