Question

9) Suppose we have a sample of the heights of Davis students and want to use the sample meanto get a confidence interval for the mean height in the population. Which of the followingwould increase the width of this confidence interval? A) Switching from a 95% confidence interval to a 90% confidence interval B) Increasing the sample size used to calculate the sample mean. C) Switching from a 95% confidence interval to a 99% confidence interval D) All of the above 10) 10) The f-statistic is calculated by dividing A) the OLS estimator by its standard error, B) the estimator minus its hypothesized value by the standard error of the estimator. C) the slope by the standard deviation of the explanatory variable. D) the slope by 1.96.

Answer 1

9) $width \ of \ confidence \ interval = 2*Margin \ of \ error$

  $Margin \ of \ error= z_{\alpha/2}SE$

$SE=Standard \ error$

$at \ 95\% CI \ z_{\alpha/2}= 1.96$

$at \ 99\% CI \ z_{\alpha/2}= 2.58$

Since 2.58>1.96

So, (C) is correct

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10.

$t = \frac{\overline{x}-\mu}{s/ \sqrt{n}}$

(B)