Sampling survey to the total area of the forest of Heshun county in Shanxi province in year 2000
Implementation steps:
- Calculate the optimal sample size n according to the known precision requirement;
- Randomly extract n sample pixels from 2,697,460 pixels with computer pseudo-random number;
- Calculate the mean of sampling pixels, then multiply 2,697,460, the result is estimated total area (unit m2 ) , and estimate the sampling precision.
Calculate:
-
The absolute error of the average forest area of each pixel (sample unit) is
The total sample size is 101 in fact
The sampling size after extending 10% is 112- Estimate the total forest area according to the mean of 112 sampling pixels:
Sample variance:
Sampling precision:
of the forest area in pixel ;
Confidence level 
；
All the image pixel size
N
in the re search areas;
Sample value 
；
Sample mean
.