区位商数（Location Quotient，LQ），是一个区域经济学与经济地理学常用的指标，用来衡量一个区域的特定产业重要程度。

其中：

若以全国作为比较的参考地区，则

Economic base analysis was developed by Robert Murray Haig in his work on the Regional Plan of New York in 1928. Briefly, it posits that activities in an area divide into two categories: basic and nonbasic. Basic industries are those exporting from the region and bringing wealth from outside, while nonbasic (or service) industries support basic industries. Because of data problems, it is not practical to study industry output and trade flows to and from a region. As an alternative, the concepts of basic and nonbasic are operationalized using employment data.