B.4 Classic Blue Pullovers Data

This is a data set consisting of 10 measurements of 4 variables. The story: A textile shop manager is studying the sales of ``classic blue" pullovers over 10 periods. He uses three different marketing methods and hopes to understand his sales as a fit of these variables using statistics. The variables measured are

$X_{1}$: Numbers of sold pullovers,
$X_{2}$: Price (in EUR),
$
X_{3}$: Advertisement costs in local newspapers (in EUR),
$X_{4}$: Presence of a sales assistant (in hours per period).

Sales Price Advert. Ass. Hours
1 230 125 200 109
2 181 99 55 107
3 165 97 105 98
4 150 115 85 71
5 97 120 0 82
6 192 100 150 103
7 181 80 85 111
8 189 90 120 93
9 172 95 110 86
10 170 125 130 78