Module 2.2 Unit 5 Assignment 1

Cross Tabs

[Total marks =25]

1. When do we categorize data? [2]

1. Which data is commonly used for cross-tabs? [3]

1. How can you use calculate RR or OR in EPINFO with data from cross tabs?

Using EPINFO

Go to Epi info at CDChttps://www.cdc.gov/epiinfo/index.html

DOWNLOAD appropriate for you

Look for statcalc

Open EPINFO

Statcalc

ed * black Crosstabulation
	black	Total
0	1
ed	0	Count	4602	1140	5742
% within ed	80.1%	19.9%	100.0%
1	Count	3373	675	4048
% within ed	83.3%	16.7%	100.0%
2	Count	3629	327	3956
% within ed	91.7%	8.3%	100.0%
3	Count	2144	493	2637
% within ed	81.3%	18.7%	100.0%
Total	Count	13748	2635	16383
% within ed	83.9%	16.1%	100.0%

What are the odds ratios being black for ed 0, 1 and 3 using 2 as the reference group? [15]

Interpret your findings

Calculate ORs for these data below [5]

Alcohol	Liver cancer	Controls
Yes	30	18
No	70	82
Total	100	100

What is the odds ratio of alcohol drinking to liver cancer?

Interpret your findings

Module 2.2 Unit 5 Assignment 2

Chi-square test

Total grades = 30 marks

1. Using the table provided below: [15 marks]

continues Table 18.12 Observed and expected frequencies for the estrogen trial illustrative example. Observed frequencies Cases Noncases Treatment group 751 7755 8506 Control group 623 7479 8102 1374 15,234 16,608 Expected frequencies Cases Noncases Total Treatment group 703.712 7802.288 8506 Control group 670.288 7431.712 8102 Total 1374 15,234 16,608 Example of calculation: Ecee = (8506)(1374)/16,608 = 703.712.Illustrative Example: Case-control data (Alcohol and esophageal cancer). Data for this example come from a case-control study on esophageal can- cer. Cases were men diagnosed with esophageal cancer from a region in France. Controls were selected at random from electoral lists from the same geographic region. Table 18.15 cross tabulates the data for cases and con- trols based on daily alcohol consumption dichotomized at 80 grams/day. Table 18.15 Alcohol and esophageal cancer illustrative case- control data. Alcohol Esophageal cancer grams/day Cases Noncases Total 280 96 109 205 80 104 666 770 Total 200 775 975 Source: Tuyns, A. J., Pequignot, G., & Jensen, O. M. (1977). [Esophageal can- cer in Ille-et-Vilaine in relation to levels of alcohol and tobacco consumption. Risks are multiplying]. Bulletin du Cancer, 64(1), 45-60. Data stored online as individual records in the file BD1. * as variables ALC2 and CASE. Data set from APHA data exchange, November 1988