Exercise

# How to lag?

Possibly, customers do not immediately react to price reductions of **Hoppiness**. Therefore, it is important to check if the effect of price promotion might extend to the next week. You can do this by adding **lags** into your model.

Lagging a variable means shifting the time base back by a given number of observations. This can be done by using the function `lag()`

. The `lag()`

function takes only one argument; `n = 1`

, by default for defining the number of periods to be shifted.

You apply `lag()`

on `PRICE`

and compare the result to the original `PRICE`

by using the function `cbind()`

. To display only the first six elements of the data columns, you can use the function `head()`

.

Instructions

**100 XP**

- Calculate a lagged
`PRICE`

variable by using the function`lag()`

. - Compare the lagged
`PRICE`

variable to the original`PRICE`

variable by using the functions`cbind()`

and`head()`

.