Author Question: Briefly explain the confounds of instrumentation and mortality. What will be an ideal ... (Read 23 times)

tsand2 · **on:** Jun 19, 2018

Briefly explain the confounds of instrumentation and mortality.

What will be an ideal response?

Question 2

Under what circumstances is a stratified random sample the most appropriate sampling method?

What will be an ideal response?

Athena23 · **Reply #1 on:** Jun 19, 2018

Answer to Question 1

Instrumentation is a threat to internal validity in which changes in the dependent variable may be due to changes in the measuring device. Mortality, or attrition, is a threat to internal validity in which differential dropout rates may be observed in the experimental and control groups, leading to inequality between the groups.

Answer to Question 2

A stratified random sample is appropriate when researchers want to describe and compare different subgroups that make up a population. This type of sampling ensures that each subgroup will be represented with a guaranteed number of participants. Note, a stratified random sample is a probability sample, so the entire population must be known.