Answer to Question 1
Experiment: investigator controls or modifies the environment and observes the effect of the variable under study
An illustration of an experiment: A doctor prescribes different drug dosages to different people to determine effectiveness.
Survey: investigator collects data by sampling a population but not modify the environment.
An illustration of a survey: A researcher stops people in a mall and asks them about the medicines they take and its effectiveness.
Answer to Question 2
Lack of variability in a quantitative response variable tends to indicate lack of precision in the tool of measurement. For example, if the heights of chair seats in classroom are reported to be 17, when, in fact, the heights vary from 16 to 17 , then lack of precision in the measuring instrument is present.