Table 3

Z-Test results for discrete buffer analysis. Results labeled with * are significant using p < 0.01.

Buffer radius (miles)

0.25

0.5

1

2

4

Gasoline stations:

Geocoded home locations:

School

13.02%

26.37%

63.45%

92.32%

99.18%

Home

8.20%

28.63%

66.37%

88.01%

97.76%

Difference

4.82%*

-2.26%*

-2.92%*

4.31%*

1.42%*

Tract centroid:

School

13.02%

26.37%

63.45%

92.32%

99.18%

Home

2.71%

17.57%

60.56%

83.56%

89.78%

Difference

10.31%*

8.80%*

2.90%*

8.76%*

9.41%*

BG centroid:

School

13.02%

26.37%

63.45%

92.32%

99.18%

Home

3.63%

20.97%

61.57%

85.14%

95.92%

Difference

9.39%*

5.40%*

1.88%*

7.18%*

3.26%*

AIRS facilities:

Geocoded home locations:

School

5.58%

16.87%

53.44%

84.36%

97.95%

Home

6.76%

25.20%

56.30%

82.57%

97.86%

Difference

-1.18%*

-8.33%*

-2.86%*

1.79%*

0.08%

Tract centroid:

School

5.58%

16.87%

53.44%

84.36%

97.95%

Home

1.44%

14.45%

57.04%

80.28%

97.60%

Difference

4.14%*

2.42%*

-3.60%*

4.08%*

0.34%*

BG centroid:

School

5.58%

16.87%

53.44%

84.36%

97.95%

Home

2.88%

17.80%

57.16%

81.46%

97.23%

Difference

2.70%*

-0.93%*

-3.72%*

2.90%*

0.72%*

TRI facilities:

Geocoded home locations:

School

0.18%

0.79%

6.01%

30.29%

70.73%

Home

0.34%

1.55%

7.78%

28.52%

70.71%

Difference

-0.16%*

-0.76%*

-1.78%*

1.77%*

0.03%

Tract centroid:

School

0.18%

0.79%

6.01%

30.29%

70.73%

Home

0.55%

3.23%

6.95%

30.54%

70.09%

Difference

-0.37%*

-2.44%*

-0.95%*

-0.25%

0.64%*

BG centroid:

School

0.18%

0.79%

6.01%

30.29%

70.73%

Home

1.20%

3.40%

6.69%

31.32%

69.72%

Difference

-1.02%*

-2.62%*

-0.69%*

-1.03%*

1.02%

Zandbergen and Chakraborty International Journal of Health Geographics 2006 5:23   doi:10.1186/1476-072X-5-23