Lab6/G4

 

Please calculate by hand  (deviation method and short cut), SAS and SPSS , and answer to the following questions.  DUE 9/26 (at labe time). Please type and be complete in your answers.

 

Use some sociological imagination in understanding the events that transpire. Outside research is always advantageous.

New Procedures:

General Form for PCSAS:                                                                                                 In SPSS/PASW

                                                                                              Analyze>Descriptive (drag variables over)>Frequencies (check statistics that you desire)

Proc Univariate data=data set name;

Var            variable-list;

Run;

 

Exercise 12           Mean and Standard Deviation for a Population

Sudden Cardiac Deaths on the Day

of a Major Earthquake

 

 

Statistical Guide:  The mean is the balance point in a distribution.  It is the most popular average.  The standard deviation is a measure of the variability of the scores around their mean.  The less scores vary (that is, differ from their mean), the smaller the standard deviation.  In the extreme case, if all the scores for a group are the same, then each score equals the mean and the standard deviation equals 0.00.

 

Background Notes:  On an average day in Los Angeles, the number of sudden deaths from cardiac causes is about 4.6.  On the day of the Northridge Earthquake there were 25 such deaths, 24 of which occurred after 4:31 a.m., when  the earthquake struck.

 

Making Predictions:  Before examining the data below, predict the results you will obtain.  (When scientists make predictions, they are hypothesizing.)  Note that your predictions are not right or wrong.  Rather, they represent your best guess as to the outcomes you will obtain.  After you perform the calculations, you will be able to determine whether the data support your predictions.

 

*1.         Predict whether the average male or the average female who died from sudden cardiac causes on the day of the earthquake was older.

            A.        Average female was older.        B.  Average male was older.

 

*2.         Explain your reasoning for the choice you selected in question 1.

 

*3.         Predict whether the ages of the males or the ages of the females who died on the day of the earthquake were more variable.

            A.        Ages of males were more variable.

            B.         Ages of females were more variable.

 

*4.         Explain your reasoning for the choice you selected in question 3.

 

Data:  The ages of females and males who died of sudden cardiac causes after 4:31 a.m. on the day of the Northridge Earthquake are given in Tables 1 and 2, respectively.

 

            Table 1 Ages of females who died                                                      

                                                        66, 92, 75, 84, 83, 80                             

 

            Table 2 Ages of males who died                                                                     

           90, 38, 45, 47, 79, 75, 71, 68, 51, 55, 56, 56, 59, 67, 66, 62, 62, 64  

 

 

Calculations:

 

5.         Calculate the means and standard deviations of the ages for males and females to
            two decimal places and enter them in Table 3.  (Note:  The data are for the entire
            population that died after 4:31 a.m. on the day of the earthquake.  Thus, you
            should use the formula for the standard deviation designed for use with a population
            and not the formula for estimating the population value from a sample drawn from
             a population.).  Please raw score (short-cut) methods and deviation method.

 

 

            Table 3 Means, standard deviations of ages of men and women
            who died.                                                                                                        

                                                Mean (M)                     Standard deviation (SD)             

            Females (N = 6)

            Males (N = 18)                                                                                              

 

6.         On the average, were males or females older?

 

7.         Were males or females more variable in their ages?

 

 

Checking Your Predictions:

 

8.         Based on your answers, was your prediction in question 1 confirmed?  Explain.

 

9.         Based on your answers, was your prediction in question 3 confirmed?  Explain.

 

 

Questions for Discussion:

 

*10.      Do the results of this study surprise you?  Do you need to reconsider your reasoning in
            questions 2 and 4?  Explain. (research may help)

 

*11.       Here’s a summary statement for a different study:  “On the average, seniors had higher
            scores than freshmen, but the scores of seniors were less variable than those of the
            freshmen.”  Make a similar statement about the statistics you calculated for this exercise
            (for the earthquake example above). 

 

  12.  Does the computer (SAS or SPSS) give you big S or little s? 

 Data source:  Robert A. Kloner, Good Samaritan Hospital, Los Angeles, CA.  For more information on this topic, see Leor, J., Poole, W.K. & Kloner, R.A. (1996).  Sudden cardiac death triggered by an earthquake.  The New England Journal of Medicine, 334, 413-419.  Copyright 1996 by the Massachusetts Medical Society.  All rights reserved.