Measures

Definitions and equations

Absolute density

${\text{Density}}_{\text{type}}=\frac{{\text{Count}}_{\text{type}}}{{\text{km}}^{\text{2}}}$

Relative densities

1) The modified retail food environment index (mRFEI):

$mRFEI=\frac{\text{chainsupermarkets}\text{\&}\text{grocerystores}+\text{fruitandvegetablemarkets}}{\begin{array}{c}\text{chainsupermarkets}|\text{grocerystores}+\text{fruitandvegetablemarkets}\\ +\text{fast-foodoutlets}+\text{conveniencestores}+\text{specialtystores}\end{array}}\times 100\%$

2) The weighted fast-food and restaurant mix (mRmix):

$mRmix=\frac{\text{fast-foodoutlets}+{\displaystyle {\sum }_i\left(W_i\ast {\text{full-servicerestaurants}}_i\right)}+{\displaystyle {\sum }_j\left(W_j\ast {\text{specialtystores}}_j\right)}}{\text{fast-foodoutlets}+\text{full-servicerestaurants}+\text{specialtystores}}\times 100\%$

where, i, j refers to the type of full-service restaurants and specialty stores, respectively; W_i and W_j is the weight of restaurant type i and specialty stores type j, respectively.