Sometimes, you need to combine data from two or more data sets into a single observation in a new data set according to the values of a common variable. When the data sources are two or more data sets that have a common structure, you can use a match-merge to combine the data sets. However, in some cases the data sources do not share a common structure. When data sources do not have a common structure, you can use a lookup table to match them. A lookup table is a table that contains key values.

The technique that you use to perform a table lookup is dependent on your data. This chapter focuses on using multidimensional arrays to perform table lookups and transposing SAS data sets in preparation for a match-merge.