STAT 203 Solutions HWA10

 

16.14:Expected counts are printed below observed counts

 

         Disease  NoDisease   Total

LowCal      13       47       60

         19.00    41.00

 

WellFed     25       35       60

         19.00    41.00

 

Total       38       82      120

 

Chi-Sq =  1.895 +  0.878 +

          1.895 +  0.878 = 5.546

df = 1, P-Value = 0.019

 

H0:  Disease and Diet are independent

HA:  Disease and Diet are related

Alpha = .05

Chi-Sq = 5.546

P-value = 0.019

There is sufficient evidence to conclude that Diet and Disease are related.

 

16.16:Expected counts are printed below observed counts

 

          Chosen   NotChosen Total

Women        9       93      102

         29.14    72.86

 

Men         91      157      248

         70.86   177.14

 

Total      100      250      350

 

Chi-Sq = 13.922 +  5.569 +

          5.726 +  2.290 = 27.508

df = 1, P-Value = 0.000

 

H0:  Chosen and Sex are independent

HA:  Chosen and Sex are related

Alpha = .01

Chi-Sq = 27.508

P-value = 0.000

There is sufficient evidence to conclude that Sex and Chosen are related.

 

16.22:

 

We combine the Mild and Moderate columns.

Expected counts are printed below observed counts

 

      MildModerate  Severe    Total

Aspirin    460       49      509

        444.33    64.67

 

NoAspirin  653      113      766

        668.67    97.33

 

Total     1113      162     1275

 

Chi-Sq =  0.553 +  3.798 +

          0.367 +  2.524 = 7.242

df = 1, P-Value = 0.007/2 = .0035 (division by 2 since test is one tailed)

 

 

H0:  Aspirin has no effect on severe strokes

HA:  Aspirin reduces severe strokes

Alpha = .01

Chi-Sq = 7.242

P-value = 0.0035

There is sufficient evidence to conclude that Aspirin reduces risk of severe strokes.