The Essentials of Biostatistics for Physicians, Nurses, and Clinicians

142 CHAPTER 8 Contingency Tables

Table 8.15

Relationship Between Reported Health

Status and Smoker vs. Non-smoker

Categories

Reported

health status

Current

smoker

Quit

smoking

Never

smoked

Total

Excellent 20 42 40 102

Good 250 300 285 835

Poor 117 72 70 259

Very poor 29 18 12 59

Total 416 432 407 1255

Table 8.14

Relationship Between Reported Health

Status and Smoking Usage

Reported

health status

Smoked 250 or

more cigarettes

Smoked 0 to

249 cigarettes

Total

Excellent 30 72 102

Good 350 485 835

Poor 121 138 259

Very poor 39 20 59

Total 540 715 1255

Why is the chi - square test appropriate here?

4. 
   

   In the same survey, the subjects also were asked to classify themselves
   according race, with the choices African American, Asian, Hispanic, Native
   Americans, or European American. Twelve subjects failed to respond.
   Table 8.16 shows race versus smoking status.
   Is race related to smoking status? Test at 5%. Should you do the test
   one - sided or two - sided? Is the chi - square an appropriate test? Does it matter
   that 12 subjects did not respond? If a much higher percentage of the sub-
   jects did not respond what might invalidate the analysis?

   
   


5. 
   

   Again using the same survey data, suppose we have statistics at baseline
   regarding the subjects drinking status, as well as their smoking status.
   Given the results in the following table, what would you conclude about
   the relationship between smoking status and drinking status? Test at the 5%
   level (Table 8.17 ).