Correlation And Regression

Question 1

Types of correlation

Answer 1

No correlation
Non linear
Moderate linear
Perfect

Question 2

What is the PMCC ( product moment correlation coefficient)

Answer 2

Type and strength of correlation between 2 variables by a line of best fit

Question 3

Notation for PMCC

Answer 3

R = between -1 and 1

Question 4

What is a regression line

Answer 4

Scatter graph shows correlation you can draw a line of best fit
Y = bx + a

Question 5

How to work out

Question 6

How to work out a , b , r

Answer 6

In calculator

Question 7

Steps in hypothesis testing

Answer 7

1. Hypothesis
2. Data
3. Critical value
4. Compare
5. Conclusion

Question 8

1. Hypothesis

Answer 8

Ho:row=0 ( Ho= null hypothesis)
No correlation = H1( alternative hypothesis) = not equal to 0 = 2 tail test
Positive correlation = H1:row>0 1 tail test
Negative correlation = H1:row<0 1 tail test

Question 9

2. Data

Answer 9

N=given
Significance level = given ( percentage)
Type of tail test ( if 2 divide percentage by 2)
Eg 10%=5% per tail
R= work out or given

Question 10

3. Critical value

Answer 10

Find critical value in formula book
If 2 (+/- that number )
Negative correlation (-)
Positive correlation (+)
Draw a number line from -1 to 1 and plot r and critical value ( shade in most left or right side )
R in shaded part = critical region or not ( alternative region )

Question 11

4. Compare

Answer 11

If r< cv
Reject null hypothesis, accept alternative hypothesis
If r> cv , accept null hypothesis and reject alternative hypothesis

Question 12

5. Conclusion

Answer 12

Conclusion = this means that there is enough / not enough evidence to suggest a correlation between x and y