Sampling survey to the total area of the forest of Heshun county in Shanxi province in year 2000
- Calculate the optimal sample size n according to the known accuracy information ;
- 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 m 2 ), and estimate the sampling accuracy.
Calculate:
- The absolute error of average forest area of each pixel is
The total sample size is 84 in fact
The sampling size after extending 10% is 93- Estimate the total forest area according to the mean of 93 pixels:
Sampling accuracy :
of the forest area in pixel ；
Confidence level 
；
All the image pixel size
N
in the research areas
;
Sample value 
；
Sample mean
；
Spatial correlation coefficient 
；
Sample variance 