Table 3.
Descriptive statistics of variables
| Category | Variable | Type | 2009 | 2017 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Min | Max | Mean | SD | Min | Max | Mean | SD | |||
| Response variable | Online purchases | Continuous | 0 | 265 | 3.4 | 6.3 | 0 | 198 | 4.2 | 6.4 |
| Socioeconomic characteristics | Average member age | Continuous | 18 | 92 | 52.7 | 14.2 | 18 | 92 | 57.6 | 23.8 |
| Male percentage | Continuous | 0 | 100 | 44.2 | 33.2 | 0 | 100 | 45.2 | 34.6 | |
| Household size | Continuous | 1 | 14 | 2.6 | 1.3 | 1 | 10 | 1.7 | 0.7 | |
| Household income ($000) | Discrete | 5 | 100 | 64.4 | 29.7 | 10 | 2000 | 72.7 | 53.2 | |
| Adult percentage | Continuous | 11.1 | 100 | 86.2 | 21.7 | 33.3 | 100 | 89.1 | 5.4 | |
| No high school percentage | Continuous | 0 | 100 | 2.7 | 14.3 | 0 | 100 | 3.7 | 15.9 | |
| Bachelor’s degree percentage | Continuous | 0 | 100 | 25.2 | 37.4 | 0 | 100 | 24.8 | 37.7 | |
| Number of vehicles | Continuous | 0 | 27 | 2.3 | 1.1 | 0 | 12 | 1.9 | 1.2 | |
| Home ownership | Binary | 0 | 1 | 0.9 | 0.3 | 0 | 1 | 0.8 | 0.4 | |
| Trip characteristics | Number of trips per day | Continuous | 1 | 52 | 7.4 | 4.7 | 1 | 60 | 7.3 | 4.5 |
| Travel time per day (minutes) | Continuous | 0.2 | 1230 | 21.8 | 30 | 0.4 | 2040 | 42.9 | 60.1 | |
| Gas price (cents/gallon) | Continuous | 149.5 | 446 | 285.6 | 94.5 | 201.3 | 295.1 | 240.3 | 22.8 | |
| Shopping trip percentage | Continuous | 0 | 100 | 23.8 | 25.5 | 0 | 100 | 9.9 | 13.9 | |
| Land use characteristics | Urban area | Binary | 0 | 1 | 0.1 | 0.3 | 0 | 1 | 0.1 | 0.3 |
| Population density | Discrete | 50 | 30,000 | 3146.4 | 4577 | 50 | 30000 | 3770 | 5,365 | |
| Internet use | Daily Internet use | Binary | 0 | 1 | 0.8 | 0.4 | 0 | 1 | 0.9 | 0.3 |