Annual period
 
Proportion of high overlap area classified as:

Mean elevation (metres)


 
Built up & bare ground

Crops & open savannah

Seasonally flooding grassland

Woodland & dense savannah (2tailed)
 

Dec 1998  Nov 1999

Cases

10.48%

61.05%

10.09%

18.38%

1098.27


Controls

10.19%

55.21%

12.15%

22.44%

1095.37


Difference

0.29%

5.84%

−2.06%

−4.07%

2.90


pvalue

0.72

>0.99

>0.99

<0.001

>0.99

Dec 1999  Nov 2000

Cases

6.96%

48.86%

26.38%

17.13%

1066.31


Controls

4.54%

59.61%

11.04%

24.81%

1100.10


Difference

2.42%

−10.76%

15.34%

−7.67%

−33.79


pvalue

>0.99

<0.001

<0.001

<0.001

<0.001

Dec 2000  Nov 2001

Cases

1.54%

52.66%

17.14%

28.66%

1058.35


Controls

7.88%

59.56%

9.53%

23.03%

1099.74


Difference

−6.34%

−6.90%

7.61%

5.64%

−41.39


pvalue

<0.001

<0.001

<0.001

<0.001

<0.001

Dec 2001  Nov 2002

Cases

0.90%

33.68%

41.60%

14.06%

1047.82


Controls

5.81%

60.84%

10.02%

23.34%

1093.86


Difference

−4.91%

−27.15%

31.58%

−9.27%

−46.04


pvalue

<0.001

<0.001

<0.001

<0.001

<0.001


Pvalues shown represent the significance of the difference in proportion (for land cover classes) from a ztest, or difference in mean (for elevation) from a ttest. The alternative hypotheses for the proportion of built up and bare ground and crops and open savannah classes and mean elevation were that the proportion or mean for case high overlap areas would be lower than for control high overlap areas (onetailed test). The alternative hypothesis for the seasonally flooding grassland class was that the proportion would be higher for case high overlap areas than control high overlap areas (onetailed test). The alternative hypothesis for the woodland and dense savannah class was that the difference in proportions would not be zero (twotailed test).