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Using data from 40 counties in England and Wales, it has been calculated that the correlation between the level of trampoline ownership and the number of neck injuries is 0.75.
Which TWO of the statements shown follow this?A High levels of trampoline ownership in a given county cause high levels of neck injuries.
B There is a strong relationship between the level of trampoline ownership and the number of neck injuries.
C 56% of the variation in the level of neck injuries from one county to the next can be explained by the corresponding variation in the level of trampoline ownership.
D 75% of the variation in the level of neck injuries from one county to the next can be explained by the corresponding variation in the level of trampoline ownership.
Answer B and C
Why not A and C?
I am confused in A and B.Is there any reading (like greater than 0.5 to be strong.)?
Secondly, why A is incorrect?
A is wrong because correlation only ever shows that two variables move closely together, but never proves that one is necessarily causing the other.
There is no fixed level at which a relationship is said to be strong because it also depends on how many counties (in this case) are looked at. As I do state in the lectures, if they had only looked at 2 countries then the coefficient of correlation would automatically be 1, but that doesn’t mean anything!!
Exactly professor. If there is no such reading so in exam how I will figure it out that there is strong relationship, partial relationship or perfect relationship?
Firstly, 75% does seem pretty good given that they have taken a lot of counties.
Secondly, and more certain here, A and D are definitely not correct, so the answer has to be B and C.
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