1. Bivariate Data

2. Bivariate data Sets of data represented by two variables.
Eg. no. of electrical appliances vs Cost of electricity bill.
Independent variable – no. of appliances
Dependent variable – electricity bill

3. For each of the following, state the independent and dependent variables. 1. House prices and the no. of bedrooms in those houses 2. Gelato sales and the temperature 3. No. of hours spent studying for a Mathematics test and the score on that test.

4. Scatter plots - Used to display bivariate data Dependent variable
Independent variable

5. Example

6. correlation Form – linear or non-linear
Direction – positive or negative
Strength – strong, moderate or weak
Linear
Non- linear

7. Positive
Negative

9. Draw a scatterplot for the following data.
Max temp 20 22 24 25 26 28 30 31
Gelato sales
165
180
200
223
250
271
285
300
Describe the correlation between the two variables.
Linear or non-linear?
Positive or negative?
Strength?
Make conclusions about the relationship between temperature and gelato sales.

11. Confidence Predicted values are only indications of what might happen
Interpolation – prediction within range of points. More confidence.
Extrapolation – prediction outside range of points. Less confidence.