9.6 Suppose that n = 50, i.i.d. observations for (Yi, Xi) yield the following regression results:

Another researcher is interested in the same regression, but makes an error when entering the data into a regression program: The researcher enters each observation twice, ending up with 100 observations (with observation 1 entered twice, observation 2 entered twice and so forth).

a. Using these 100 observations, what results will be produced by the regression program? (Hint: Write the “incorrect” values of the sample means, variances, and covariances of Y and X as functions of the “correct”
values. Use these to determine the regression statistics.)

b. Which (if any) of the internal validity conditions are violated?

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49.2 73.9X, SER = 13.4, R2 = 0.78. (23.5) (16.4)