A study was conducted to assess whether the abundance of particular bacterial species in the gastrointestinal system is associated with the development of colon cancer.

The following data matrix shows a subset of the data collected in the study. Cancer stage is coded 1-4, with larger values indicating cancer that is more difficult to treat. The abundance levels are given for five bacterial species; abundance is calculated as the frequency of that species divided by the total number of bacteria from all species.

(a) What does each row of the data matrix represent?

(b) Identify explanatory and response variables.

(c) For each variable, indicate whether it is numerical or categorical.

Transcribed Image Text:

age gender stage bug 1 bug 2 bug 3 bug 4 bug 5 1 71 Female 2 0.03 0.09 0.52 0.00 0.00 2 53 Female 4 0.16 0.08 0.08 0.00 0.00 3 55 Female 2 0.00 0.01 0.31 0.00 0.00 4 44 Male 2 0.11 0.14 0.00 0.07 0.05 73 48 Female ...3 0.21 0.05 0.00 0.00 0.04