Correlations Flashcards
(8 cards)
1
Q
r measures only the strength of…
A
linear relationships between X,Y
2
Q
correlation coefficient function
A
loool look it up
3
Q
Sim + Dif of co variance to correlation
A
S: cov(X,Y)>0 indicates a positive relationship
D: Isn’t a standardised measure therefore the absolute value isn’t reliable indicator of relationship strength
4
Q
Calculation r in relation to cov(X,Y)
A
cov(X,Y)/(Sx*Sy)
5
Q
r and cov stat if X,Y= independent
A
0
6
Q
What does r^2 measure
A
Proportion of Y variability explainable by X
7
Q
Indirect causality
A
When third variable exists e.g. ‘Z’
X may affect Z which in turn effects Y
8
Q
Limitations of correlation coefficient
A
Only linear relationships
Correlation meaningless for categorical data
