Geoscience Reference
In-Depth Information
TABLE 2.2
Results from a Strip Transect Survey of Winter Mortality of Deer
Habitat
Transect
I
II
III
1
1
1
0
2
1
0
0
3
2
0
0
4
2
0
0
5
0
1
0
6
0
0
0
7
0
0
0
8
0
0
0
9
1
1
0
10
2
0
1
11
2
1
0
12
0
0
2
13
2
0
1
14
1
0
0
15
0
0
1
16
2
17
0
18
0
19
1
20
1
n
20
15
15
y
i
0.90
0.27
0.33
s
i
0.85
0.46
0.62
0.036
0.014
0.025
Var(
y
)
i
N
20,000
15,000
15,000
Note:
The observations are the number of dead deer found in 1 km by 60
transects in three different habitat types.
·
=
50,000 × 0.097 = 4,850, and an approximate 95% confidence interval for
the population total is 27,000 ± 1.96 x 4,850 or 17,500 to 36,500.
T
y
= 50,000 × 0.540 = 27,000, with estimated standard error
SE()
T
2.9.1 Poststratification
With some variables that are suitable for stratification, it is difficult to know
the strata to which units belong until a survey has been conducted, although
the strata sizes are known accurately for the population. For example, the
stratification of sample quadrats on the basis of habitat type may not be pos-
sible until the quadrats have been visited.
