Lab connect Session: LAB 3 Biostat 501 Lab connect Session: LAB 3

GENERAL REMINDERS Please make sure to look at the Homework and lab solution posted on Canvas. If you have confusion/ question about the solution, please post it on the Canvas Discussion thread. Homework assignments are due by 5pm on Sunday. Lab assignments are due by 5pm on Thursday. GSI Office hours: Thursdays 6-7 PM, same link as the Lab Connect session. The session will be recorded and posted in the Weekly To do page.

LAB REMINDERS The Lab Connect Sessions will be recorded and posted in Canvas. The Lab power point slides will be added to the Lab Files Folder in Canvas. If you have to miss a Connect session, you are responsible for watching the recording at your convenience, completing all the materials in the To Do list, and turning in your lab assignment on time.

CONNECT Sessions Please have your Lab manual and SPSS open before each lab. Have the file smoking.sav open in SPSS for today’s lab If you have any questions through out the session, please raise your hand and I will get to you as soon as possible.

OBJECTIVES 1. Select a random subsample from a larger dataset. 2. Generate a random sample from a given Normal distribution. 3. Perform Normal distribution probability calculations, comparing results by hand to SPSS results.

Lab 3 For this lab, I will ask you to do a few steps from the manual and then we will discuss the results. We will discuss many of the questions together in class and leave some for you to do on your own.

Variables in this data set Age – in years BMI – Body Mass Index CigsPerDay – cigarettes smoked per day CigCost – amount of money spent on one pack of cigarettes

Part 1 and II: CREATE DESCRIPTIVE STATISTICS FOR THE LARGE DATASET AND SELECTING A RANDOM SAMPLE FROM AN EXISTING FILE Please take a few minutes to do steps Part 1,II and III in your lab manual. Continue to follow the steps on page 28 till “STOP. Answer Question 1” When you are finished, please put up a check. If you have any questions on how to do this, please raise your hand.

Descriptive Statistics Descriptive Statistics Part 1 and II: CREATE DESCRIPTIVE STATISTICS FOR THE LARGE DATASET AND SELECTING A RANDOM SAMPLE FROM AN EXISTING FILE Question 1: How do the sample statistics compare to the values from the entire dataset? Descriptive Statistics   N Range Minimum Maximum Mean Std. Deviation Age (years) 835 50 20 70 46.90 10.601 BMI - Body Mass Index (kg/m2) 55.36 15.49 70.85 28.6956 6.52081 CigsPerDay - number of cigarettes smoked per day 60 10 21.59 9.247 CigCost - amount of $ spent on one pack of cigarettes 5.84 .66 6.50 4.4376 .94744 Valid N (listwise) Descriptive Statistics   N Range Minimum Maximum Mean Std. Deviation Age (years) 83 47 21 68 45.93 10.979 BMI - Body Mass Index (kg/m2) 31.59 15.96 47.55 29.0584 6.93325 CigsPerDay - number of cigarettes smoked per day 35 10 45 20.00 8.352 CigCost - amount of $ spent on one pack of cigarettes 5.05 1.00 6.05 4.3286 1.17490 Valid N (listwise)

Part iv: Generate a sample from a Normal Distribution Please take a few minutes to do part III and steps1-4 of Part 1V in your lab manual. Please attempt to answer Question 2 in the Lab Exercise 3. When you are finished, please put up a check. If you have any questions on how to do this, please raise your hand.

Part iv: Generate a sample from a Normal Distribution Question 2: Write down the mean and standard deviation of the random sample. How close are they to the population values (mean=26.5, sd=9.5)? Does the histogram look relatively normal?

QUESTION 3 Rest of the lab does not require the smoking dataset Questions 3, 4, and 5 are done by hand. Please take a few minutes to work through question 3. When you are finished, please put up a check.

Question 3 Question 3: The tick marks on the Normal curve shown below are spaced one standard deviation apart. Label each of the seven tick marks with the appropriate numeric value for the variable BMI. (mean=26.5, sd=9.5)

QUESTION 4 Questions 4 is done by hand. Please take a few minutes to work through question 4. When you are finished, please put up a check.

QUESTION 4 Question 4: On the Normal curve above, indicate the area under the curve corresponding to those who are neither overweight nor obese. Use right cross- hatches (/////). (mean=26.5, sd=9.5) -2.0 7.5 17 26.5 36 45.5 55

QUESTION 4 What proportion of the population is neither overweight nor obese? Show all of your work. (mean=26.5, sd=9.5) From the Z table, we find that this proportion is equal to 0.4364.

Question 5 Questions 5 is done by hand. Please take a few minutes to work through question 5. When you are finished, please put up a check.

Question 5 On the Normal curve above, indicate the area under the curve corresponding to those who are not obese. Use left cross hatches (\\\\) this time. (mean=26.5, sd=9.5) -2.0 7.5 17 26.5 36 45.5 55

Question 5 Showing all your work, find the proportion of the population that is not obese. (mean=26.5, sd=9.5) From the Z table, we find that this proportion is equal to 0.6443.

Part V: Normal Distribution Probability Calculations USING SPSS Please take a few minutes to do steps 1-6 of Part V in your lab manual. Please attempt to answer question 6 and 7 in Lab Exercise 3. When you are finished, please put up a check. If you have any questions on how to do this, please raise your hand.

Part V: Normal Distribution Probability Calculations USING SPSS Question 6: According to the SPSS result, what proportion of the population is neither overweight nor obese? Compare this to the proportion you found in Question 4. Question 7: According to the SPSS result, what proportion of the population is not obese? Compare this to the proportion you found in Question 5.

Part V: Normal Distribution Probability Calculations USING SPSS Please take a few minutes to do steps 7-8 of Part V in your lab manual. Please attempt to answer questions 8, 9, and 10. When you are finished, please put up a check. If you have any questions on how to do this, please raise your hand.

Part V: Normal Distribution Probability Calculations USING SPSS Question 8: What area does the expression CDF.NORMAL(30, BMIMEAN, BMISD) – CDF.NORMAL(25, BMIMEAN, BMISD) compute for you, i.e. what BMI category(ies) does this expression correspond to? What is the proportion of the population that falls in this category(ies)? -2.0 7.5 17 26.5 36 45.5 55

Part V: Normal Distribution Probability Calculations USING SPSS Question 9: Write down the expression you used to find the area to the right of a BMI cut off. Write this expression in SPSS language, in terms of CDF.NORMAL(BMICO, BMIMEAN, BMISD). -2.0 7.5 17 26.5 36 45.5 55

Part V: Normal Distribution Probability Calculations USING SPSS Question 10: On the Normal curve above, use vertical hatches (||||) to indicate the area corresponding to obese BMI’s. What proportion of the population is obese? Get the results both in SPSS and by hand. Compare your results. -2.0 7.5 17 26.5 36 45.5 55

Part V: Normal Distribution Probability Calculations USING SPSS Question 10: What proportion of the population is obese? Get the results both in SPSS and by hand. Compare your results. The area to the right of 30 should be shaded with the vertical hatches. SPSS shows that this proportion is equal to 0.36.

Questions? Remember to keep track of the Weekly To Do list Pages on Canvas. They are there for your benefit. Please be sure you have done everything on this week’s To Do list by September 29th. Please finish all the questions on the lab 3 worksheet. Scan the pages and upload it in on Canvas before 5pm Thursday. Remember to make sure all of the pages are included and correctly oriented and that I can read them.