NZ Level 8 (NZC) Level 3 (NCEA) [In development] Making Predictions from Time Series Data (using LSRL)

## Interactive practice questions

A least squares regression line is fitted to seasonally adjusted data and is given by:

$y=4.5493t+48.9941$y=4.5493t+48.9941

a

Calculate the predicted deseasonalised value for time period $15$15, to four decimal places.

b

If the seasonal index for this period was $69$69%, calculate the true predicted value to four decimal places.

Easy
Approx 3 minutes

A least squares regression line is fitted to seasonally adjusted data and is given by:

$y=-2.7698t+79.3735$y=2.7698t+79.3735

A least squares regression line is fitted to seasonally adjusted data.

For time period$t=5$t=5the predicted deseasonalised value is $44.9036$44.9036

For time period $t=10$t=10 the predicted deseasonalised value is $60.3796$60.3796

The following data shows the sales of air conditioners at a leading retailer over four quarters from 2012 to 2014.

### Outcomes

#### S8-1

Carry out investigations of phenomena, using the statistical enquiry cycle: A conducting experiments using experimental design principles, conducting surveys, and using existing data sets B finding, using, and assessing appropriate models (including linear regression for bivariate data and additive models for time-series data), seeking explanations, and making predictions C using informed contextual knowledge, exploratory data analysis, and statistical inference D communicating findings and evaluating all stages of the cycle.

#### 91581

Investigate bivariate measurement data