First, open the Master Data File and compute the mean and standard deviation for variable MISSED_HRS for all valid cases in this data file. Second, use SPSS menu (Data->Select Cases->Sandom sample of cases) to draw a random sample 1,000 cases. Using this file with 1,000 cases, compute the mean and standard deviation for variable MISSED_HRS . Repeat step 2 to select 50 cases and compute the mean and standard deviation for variable MISSED_HRS . Repeat step 2 to select 10 cases and compute the mean and standard deviation for variable MISSED_HRS . Record all means and standard deviations in this table using two decimals, which is the standard in scientific writing: VARIABLE: MISSED_HRS Number of valid Mean, Standard Deviation (SD), cases (cases without missing data) use two decimals use two decimals Al cases (about 3,017) in the Master Data File Sample of 1,000 cases Sample of 50 cases Sample of 10 cases 1. Explain what this variable shows. Use the data dictionary to examine this variable and the variables that precede it. 2. Expiain in plain English what it means to select cases from the Master Data File randomly. Take time to understand this term; it is very important to your performance on this assignment. 3. Your manager reviewed your table and other tables posted by your classmates and wants to know why the numbers are not the same (for each randomly drawn sample in your table and in tables created by different students). 4. Why are so many cases missing? Explain without using any statistical jargon, assuming that your manager never studied statistics. 5. Which of the sample statistics (means and standard deviations) are expected to be most representative of the actual mean and standard deviation in the Master Data file? Would it be statistics drawn from a sample of 1,000 cases, 50 cases or 10 cases? Why? Bonus: Review the method used by CDC researchers, https://www.cdc.govchsnhsnas.htm. Are data in the Master Data File for MISSED_HRS representative of the entire population of NAs in the United States? Why or why not? If you had to collect the same data on your own, using time and financial resources you have today, how likely are you to obtain a more representative sample than the one obtained bv the CDC researchers? VARIABLE: MISSED_HRS Number of Mean, Standard Deviation valid cases use two SD) cases without decimals use two decimals missing data All cases (about 3,017) in 168 13.04 26.61 the Master Data File Sample of 1,000 cases 59 13.56 31.12 Sample of 50 cases 6 7.17 2.04 Sample of 10 cases 2 4.50 4.95