A location quotient (LQ) is a ratio of a single location’s share of two region-wide variables. For example, the first variable might be the percent of the region’s intakes that came from the location. The second variable could be the percent of the region’s eligible population that lives in the location.
For locations where those two percentages are roughly equal, say, for example, 3% of intakes and 3% of the eligible population, the location quotient would be close to 1. The level of intakes are as expected, given the underlying eligible population.
For locations where the intakes are proportionally greater, say, for example, 4% of the intakes but only 2% of the eligible population, the location quotient would be greater than 1. The level of intakes is greater than expected, given the underlying population. The larger the LQ, the greater the concentration.
For locations where the intakes are proportionally less than the eligible population, say, for example, 2% of the intakes but 4% of the eligible population, the location quotient would be less than 1. Given the underlying population, there are fewer intakes than expected. Given the underlying distribution of eligible population, you would have expected a greater percentage of the region’s intakes from that particular location.
A location quotient for location i is calculated as:
A location quotient is calculated for each location in the region. It is often useful to then map a region’s location quotients. It might be that areas of over- or under-concentration cluster together, revealing interesting underlying questions about the process that generated the data.