Internal validity is to an experiment what having _____ is to a ...

[hbsimmons88]

Internal validity is to an experiment what having _____ is to a survey.
 
  a. proper control groups c. a representative sample
  b. a small sample d. a long survey instrument

Question 2

From which of the following studies can one most reasonably determine cause and effect?
 
  a. correlational study c. naturalistic observation
  b. true experiment d. all these

[smrtceo]

Answer to Question 1

C
Both of these are needed in order for the researchers to be able to make accurate conclusions using their respective techniques. Experimenters can't draw accurate conclusions about causes without internal validity, and survey researchers can't draw accurate conclusions about populations if the sample is not representative.

Answer to Question 2

B