APFIVE In a study examining the effect of the number of close friends on evening Facebook checks, a researcher uses the regression equation
$$\hat{y} = -1.73 + 0.5492*x$$
to predict Facebook checks. After rescaling the variable x by multiplying all values by 10, the researcher claims that the regression slope remains 0.5492. What mistake did the researcher make?
They inverted the regression equation, so actually the intercept would change instead of the slope.
They overlooked that scaling the predictor variable changes its standard deviation, which in turn alters the slope; the new slope should be 0.5492 divided by 10.
They mistakenly assumed that the correlation coefficient is affected by scaling, when it should remain unchanged.
No mistake was made; the regression slope is invariant under rescaling of the predictor variable.
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