Chapter 4/1 Correlation/Regression (AS/A-Level)

Question 1

x-axis

Answer 1

Independent/explanatory Variable

Question 2

y-axis

Answer 2

Dependent/response Variable

Question 3

Why may some conclusions not be valid?

Answer 3

It is possible that although variables are correlated, there is not necessarily a casual relationship.

Question 3

What is the form for a regression line

Answer 3

y = a + bx

Question 4

Interpret the y-intercept (the a value in y = a + bx)

Answer 4

Usually initial bla bla bla

Question 5

Interpret the gradient (the b value of y = a + bx)

Answer 5

e.g. For every 1 hour of revision, the exam mark increase by bla bla

Question 6

What is Interpolating?

Answer 6

Estimating a value inside the data range

Question 7

What is Extrapolating?

Answer 7

Estimating a value outside the data range

Question 8

Exponential equation

Answer 8

y = ab^x

Question 9

Re write y = ab^x in terms of logs

Answer 9

logy = loga + xlogb

Question 10

What is PMCC?

Answer 10

denoted by r, describes the linear correlation between two variables. It can take values between -1 and 1.

Question 11

r = -1

Answer 11

Perfect Negative

Question 12

r = 0

Answer 12

No correlation

Question 13

r = 1

Answer 13

Perfect Positive

Question 14

Calculate r on calculator

Answer 14

Menu -> 6 -> 2 -> Data Entry -> Regression Calc

Question 15

Comment on suitability of linear regression model

Answer 15

Because r is close to 1, correlation is very strong therefore a subitable model bla bla bla