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New Zealand Journal of Forestry Science

Table 2 Simulation Results 1 by Stand

From: Inventory estimates of stem volume using nine sampling methods in thinned Pinus radiata stands, New Zealand

Stand

Sampling Method

Bias (%) 2

Design Effect

Reliability -SRS (%)

Reliability – Cluster (%) 3

1

Random

−0.28

1.000

94.6

 

1

Stand-boundary

***13.52

0.624

0.1

 

1

Quasi-random group

0.08

0.967

94.8

93.8

1

Zigzag line

−0.12

1.019

94.5

 

1

Grid (0.01 ha plot)

0.14

1.043

94.3

91.4

1

Grid (0.02 ha plot)

−0.11

0.934

95.2

93.8

1

Grid (0.04 ha plot)

0.11

1.025

94.5

91.0

1

Grid (0.08 ha plot)

*0.23

1.114

94.1

90.8

1

Single- point

−0.28

2.311

81.2

 

2

Random

−0.12

1.000

94.2

 

2

Stand-boundary

***12.77

0.650

9.0

 

2

Quasi-random group

***-0.98

1.161

91.2

83.8

2

Zigzag line

***-0.74

0.844

95.8

 

2

Grid (0.01 ha plot)

0.10

0.776

97.7

92.1

2

Grid (0.02 ha plot)

0.24

1.073

95.5

88.3

2

Grid (0.04 ha plot)

0.20

1.100

93.5

89.8

2

Grid (0.08 ha plot)

0.06

1.368

92.1

88.8

2

Single-point

0.12

3.551

63.0

 

3

Random

0.06

1.000

94.0

 

3

Stand-boundary

***2.83

0.378

95.9

 

3

Quasi-random group

**-0.28

1.087

93.9

82.1

3

Zigzag line

**0.26

0.780

96.4

 

3

Grid (0.01 ha plot)

−0.09

0.924

94.9

84.9

3

Grid (0.02 ha plot)

0.15

0.767

96.7

85.9

3

Grid (0.04 ha plot)

**0.34

1.651

88.0

66.8

3

Grid (0.08 ha plot)

−0.06

1.713

84.7

65.1

3

Single-point

***-0.47

1.314

89.7

 

4

Random

−0.13

1

94.8

 

4

Stand-boundary

***11.54

0.487

13.8

 

4

Quasi-random group

−0.07

0.922

96.8

89.7

4

Zigzag line

***-0.99

1.070

93.4

 

4

Grid (0.01 ha plot)

0.30

1.050

95.2

86.8

4

Grid (0.02 ha plot)

**0.43

1.112

94.7

82.6

4

Grid (0.04 ha plot)

0.10

0.940

96.6

83.2

4

Grid (0.08 ha plot)

−0.23

1.411

90.2

72.0

4

Single-point

***-2.78

1.120

87.9

 

5

Random

−0.10

1.000

95.2

 

5

Stand-boundary

***12.76

0.644

4.1

 

5

Quasi-random group

0.14

1.124

94.4

87.0

5

Zigzag line

***-0.72

1.264

90.1

 

5

Grid (0.01 ha plot)

0.21

1.566

89.6

82.7

5

Grid (0.02 ha plot)

0.18

1.176

93.5

86.2

5

Grid (0.04 ha plot)

0.30

1.642

91.5

78.3

5

Grid (0.08 ha plot)

−0.15

1.192

93.4

81.4

5

Single-point

***-1.16

1.820

83.2

 
  1. 1Each row in this table is a summary of the thousand samples drawn from the respective stand under the specified sampling method.
  2. 2Where the Bias is significantly different from zero, the level of significance is indicated by asterisks; *, ** and *** indicate 5, 1 and 0.1% respectively.
  3. 3Reliability under cluster sampling is calculated only for the plot-based methods.
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