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

From: The mechanisms responsible for 2-dimensional pattern formation in bacterial macrofiber populations grown on solid surfaces: fiber joining and the creation of exclusion zones

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.