5 - correlation and regression Flashcards
1
Q
pearsons product moment correlation coefficient (r)
A
Sxy/ root(SxxSyy)
-1<r<1
- linear relationship
- normal distribution
2
Q
affect of linear coding on r
A
does not affect the correlation coefficient
3
Q
hypothesis testing of r
A
H0 p = 0
H1 p</> 0 (1 tail)
H1 p!= 0 (two tail)
if r > test stat (find in table) reject H0
4
Q
spearman rank
A
- it’s the correlation coefficient of the ranks of each value
- any distribution
- non linear
5
Q
spearman rank (rs) =
A
1 - 6sum(d^2) /n(n^2 -1)
6
Q
hypothesis testing
A
H0 - no association
H1 - positive or negative association (1 tail)
H1 - is association (2 tail)
7
Q
min sum of d^2 thats not 0
A
2
8
Q
how to show the regression line
A
want to minimise the distance from each point to the line
