Hi,

Question

I have answered some questions for some homework and I've got one of them wrong. I cannot modify my answer but I would really love to know why my answer is wrong.

This is the statement of the problem:

n this series of questions, we examine data from a study of 158 infants who visited Northbay Healthcare in Solano County, California for a Vitamin K shot. Assume that the infants in the study are a representative random sample from all infants in Northbay Healthcare.

Nurses administered a Vitamin K shot to each infant. Infants were randomized to two different protocols to study how to reduce pain experienced by the infants due to the shot. The infants were divided into two groups – the control group, where standard protocol for handling the infants was used; and an intervention group, where mothers held their infants prior to, during, and after administration of the shot. Pain was measured using the Neonatal Infant Pain Score (NIPS) (Lawrence et. al 1993). The variables in the dataset are described below:

id – unique identifier for each infant
group – 1 if intervention group, 0 if control
pain0 – NIPS score 0 seconds after shot
pain30 – NIPS score 30 seconds after shot
pain60 – NIPS score 60 seconds after shot
pain120 – NIPS score 120 seconds after shot
crytime – total time that the infant cried in seconds

And the question:
Assuming randomization was successful and all participants complied with their assigned exposure, which of the following should we be concerned about:
Confounding by sex of the infant
Confounding by the amount of pain experienced by the infant
Effect modification by sex of the infant
Misclassification of the exposure status of the infant

My answer was:
Confounding by the amount of pain experienced by the infant

Could anyone help me reason why I am wrong?

Thanks!

Answer 1

Your answer is nuts. Reason? I am wondering if you know what a confounding variable is? It is something that has a relationship to the independent variable, thus may be related to the dependent variable.
Your answer, the amount of pain, is the dependent variable NIPS score. You need to be searching for something that may be related to the kids getting the shot, or how much pain the registered.

Did boys get the shot more frequently than girl infants? Do boy babies whine more than girls getting a shot? (confounding by gender of infant)
(confounding by effect modulation)

Answer 2

Hi Bobpursley,

Thank you very much for your answer...

The problem is that I do not have any data on whether the boys got shots more frequently than girls enfants or whether boy babies whine more than girls...
I guess those could be an explanation if I had more data...
Would be misclassification an unreasonable answer as well?
Thanks for your help, I really want to understand the topic. :-)