Consider this scenario: Surgery patients in Hospital A and Hospital B are classified as being in either good condition or poor condition. When looking separately at survival rates among patients in good conduction and in poor condition, Hospital B has higher rates for both groups. Yet when the two groups are combined, Hospital A has a higher rate.

What's the most likely lurking variable?

The amount of food eaten by the patients

Which hospital

Survival rates

The number of patients in good or poor condition

The skill of the surgical staff

Question

Consider this scenario: Surgery patients in Hospital A and Hospital B are classified as being in either good condition or poor condition. When looking separately at survival rates among patients in good conduction and in poor condition, Hospital B has higher rates for both groups. Yet when the two groups are combined, Hospital A has a higher rate.

What's the most likely lurking variable?


       The amount of food eaten by the patients

       Which hospital

       Survival rates

       The number of patients in good or poor condition

       The skill of the surgical staff

anonymous · Answer

@jim_thompson5910

danjs · Answer

THe number of patients in each condition matters.

anonymous · Answer

yes, I agree with @DanJS 

the number of patients is the varying factor.

the scenario never mentions food nor does it mention skill of staff, so those are out

and the only logical one would be number of patients because that is what is being changed :)

danjs · Answer

You can model equations that will show this if you would like.