A fast food chain plans to add a new item to its menu. However, they are still undecided between three possible campaigns for promoting the new product. In order to determine which promotion has the greatest effect on sales, the new item is introduced at locations in several randomly selected markets. A different promotion is used at each location, and the first month sales of the new item recorded.

This information is collected in testmarket_1month.sav . Use the Linear Mixed Models procedure to measure the effect of each promotion on sales.