MATH 225N Week 8 Assignment: Correlation and Causation
Understand the difference between correlation and causation
Question
True or False: The more samples taken in a scientific study, the longer the amount of
time it will take to complete the research on the samples. Although there are other
factors that affect study time, such as experience and equipment, increasing the
number of samples will cause an increase in research time. Correct! You nailed it.
Understand the difference between correlation and causation
Question
Suppose that a large controlled experiment tests whether caffeine improves reaction
times. A very large number of randomly selected participants are randomly given
identical-seeming pills with varying doses of caffeine (including none) and then given
tests of reaction times under the same conditions. The experiment finds a strong
negative correlation between caffeine dose and reaction time. (Note that lower
reaction times are better.) Correct answer:
There is evidence that caffeine causes lower (better) reaction times.
Correlation alone does not prove causation, but this scenario provides more evidence
than just correlation between two variables. Since the data were obtained from an
appropriately randomized controlled experiment, a correlation can be used as
evidence of a causal relationship. Since all other variables were controlled, there is no
third variable that could be associated with caffeine that actually causes differences in
reaction times. Yes that's right. Keep it up!
