Question

For a recent report on sleep deprivation, the Centers for Disease Control and Prevention interviewed 11594 residents of California and 4878 residents of Oregon. In California, 893 respondents reported getting insufficient rest or sleep during each of the preceding 30 days, while 444 of the respondents from Oregon reported the same. Calculate a 99 % confidence interval for the difference between the proportions of Californians and Oregonians, pCalifornia−pOregon, who report getting insufficient rest. Round your answer to 4 decimal places.

Answer 1

Excel add-in (Mega Stat) procedure: Step 1: In EXCEL, Select Add-Ins> Mega Stat> Hypothesis Tests. Step 2: Choose Proportion vs. Hypothesized Value. Step 3: Choose Data Input. Step 4: In Group 1, enter the value 893 under x and enter the value 11594 under n. Step 5: In Group 2, enter the value 444 under x and enter the value 4878 under n. Step 6: Enter 0 Under Hypothesized difference. Step 7: Choose not equal in alternative. Step 8: Click OK. Excel add-in (Mega Stat) output:

Hypothesis test for two independent proportions 0.091 0.077 893/11594 893 11594 0.0812 p (as decimal) 444/4878 1337/16472 p (as fraction) 1337. X 16472 n 4878 0.014 difference 0.0047 std. error 0. hypothesized difference -00264 confidence interval 99% lower -00016 confidence interval 99% upper 0.0124 margin of error Thus the 99 % confidence interval for the difference between the proportions of Califomans regonians is Pcaijoma -Porgen (00264,-0.0016)