Explain the difference between random sampling and random assignment, and indicate how these procedures affect a study's internal and external validity

Question

What will be an ideal response?

Answer 1

A random sample indicates that all members of the target population have an equal
chance of being selected for the study. Random samples are particularly attractive
because they are more representative than other samples (such as convenience
samples) of the populations from which they are taken. Moreover, because
representative samples allow one to generalize the findings of a study to the larger
population, random sampling increases external validity. Random assignment is a
procedure that is only relevant when conducting an experiment? in this case, members
of the sample (who have already been chosen, randomly or not) have an equal chance
of being assigned to any of the experimental conditions. This procedure assures that, on
average, members of experimental groups are equivalent in all ways before a study
begins. This allows the researcher to infer that any differences between groups at the
end of the study must be the result of the manipulation. In other words, it is random
assignment that allows the researcher to conclude with confidence that the independent
variable caused the changes in the dependent variable, which means that random
assignment to condition increases internal validity.