# Table 1 Comparison of 2-dimensional spatial distributions of aggregate structures in observed and theoretical populations1

Population examined6 Number of structures Number of squares Average number of structures/ grid square2 Number of grid squares containing structures
0 1 2 35
97–863
expected4
154 103 1.50
1.50
15
23.1
40
34.5
38
25.8
10
12.9
97–142
expected
115 104 1.11
1.11
19
35.1
57
38.5
26
21.1
2
7.7
916–150
expected
94 106 0.89
0.89
32
43.7
56
38.7
16
17.2
2
5.1
916–444
expected
74 106 0.70
0.70
45
52.7
49
36.8
11
12.9
1
3.0
920–125
expected
106 106 1.00
1.00
27
39.0
54
39.0
23
19.5
2
6.5
920–400
expected
94 106 0.89
0.89
36
43.7
47
38.7
22
17.2
1
5.1
1. 1. The populations shown in Figure 6 were used to obtain the observed values. 2. The grid square area within which structures were counted was 30.25 mm2. 3. Two time points (frames) were measured from each sequence: 86 & 142, 150 & 144, 125 & 400. 4. Expected values are Poisson distributions of theoretical populations with the same average number of structures per grid square. 5. Squares containing 4 (1), 5 (2) and 6 (1) are included for population 97–86. 6. Chi-square and p values were obtained by comparison of the observed and theoretical populations divided into 4 classes. Thus there are 3 degrees of freedom for all populations. The values obtained are: 97–86: 10.1, p = .017; 97–142: 21.6, p = .0001; 916–150: 12.8, p = .0048; 916–444: 6.8, p = .086; 920–125: 13.2, p = .0041; 920–400: 7.8, p = .052.