MATH 225N Week 8 Assignment; Understand the Difference Between Correlation and Causation (Collection)

Understand the difference between correlation and causation


Question
A survey regarding truck engines found a positive correlation between the size of the engine and horsepower the
engine produces. Answer the following question based only on this information.




True or false: It can be concluded that trucks with larger engines have greater horsepower.


Not quite - review the answer explanation to help get the next one.


True

False
Answer Explanation
Correct answer:
False

Correlation does not prove causation. There could be a third variable associated with size of the engine that causes
the truck to have greater horsepower. For example, it could be that manufacturers anticipate that consumers who
want trucks with greater horsepower also prefer trucks with large engines and therefore choose to make trucks
with larger horsepower.

, Your answer:
True




Find and interpret the correlation coefficient

Question
In studying the relationship between income and time spent exercising, suppose you
computed r=−0.052 using n=19 data points. Using the critical values table below, determine if the value of r is
significant or not.
df CV (+ and -) df CV (+ and -) df CV (+ and -) df CV (+ and -)
1 2
1 0.997 0.555 0.413 40 0.304
1 1
1 2
2 0.950 0.532 0.404 50 0.273
2 2
1 2
3 0.878 0.514 0.396 60 0.250
3 3
1 2
4 0.811 0.497 0.388 70 0.232
4 4
1 2
5 0.754 0.482 0.381 80 0.217
5 5
1 2
6 0.707 0.468 0.374 90 0.205
6 6
7 0.666 1 0.456 2 0.367 10 0.195