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Table IV-2. The
declining-trend threshold abundance required both to maintain at least
1,500 individuals (the abundance threshold) and to be able to detect a
10%/yr decline for different levels of precision [expressed as coefficients
of variation (CV) in abundance (N)] and at different levels
of significance |
| CV |
Significance Level for Type I (a)
and Type II (ß) Errors
|
|
a = ß = 0.005
|
a = ß = 0.25
|
Number of
Annual
Surveys
to Detect
r = -0.1 |
Initial N
to End
at 1,500 |
Number of
Quadrennial
Surveys
to Detect
r = -0.1 |
Initial N
to End
at 1,500 |
Number of
Annual
Surveys
to Detect
r = -0.1 |
Initial N
to End
at 1,500 |
Number of
Quadrennial
Surveys
to Detect
r = -0.1 |
Initial N
to End
at 1,500 |
|
0.1
|
6
|
2,733
|
12
|
4,980
|
3
|
2,025
|
8
|
3,338
|
|
0.2
|
10
|
4,077
|
16
|
7,430
|
4
|
2,238
|
12
|
4,980
|
|
0.3
|
13
|
5,504
|
20
|
11,084
|
6
|
2,733
|
12
|
4,980
|
|
0.4
|
16
|
7,429
|
24
|
16,535
|
8
|
3,338
|
12
|
4,980
|
|
0.5
|
19
|
10,029
|
32
|
36,799
|
9
|
3,689
|
12
|
4,980
|
|
0.6
|
22
|
13,538
|
36
|
54,897
|
10
|
4,077
|
16
|
7,429
|
|
0.7
|
23
|
14,961
|
40
|
81,897
|
11
|
4,506
|
16
|
7,429
|
|
0.8
|
25
|
18,273
|
44
|
122,176
|
12
|
4,980
|
16
|
7,429
|
|