sampling method..急急急!!15分

Hello,

stratified sampling and cluster sampling are the methods of
probability Sampling.

stratified sampling is a population is first divided into k mutually exclusive. It is either a proportional or a non- proportional sample is selected from each stratum.

Example:

population= 500, 抽５０　（１０％）
There are 3 groups
group1=100
group2= 200
group3=200
Total = 500
group1抽10(10%), group2抽 20(10%), group3抽 20 (10%)
total 抽 50 (10=20=20)
This is proportional!

NON Proportional example:
group1抽 16 (50÷3), group2抽 17 (50÷3), group3抽 17 (50÷3)


cluster sampling= Quasi sampling= Area- sampling, therefore it is
use area to 抽 .

Example, there are 20 Areas, only needt to 抽 5 Areas. then other
15 areas can be ignored and only care the 5 Areas and use these 5
area to 抽 others ( such as buildings, streets)

Hope my infortmation can help you!!

http://www.zhikao365.net/difficulty/200612/625.htm