# Sampling Techniques-Stratified Random Sampling (ISS (Statistical Services) Statistics Paper III): Questions 6 - 8 of 8

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## Question number: 6

» Sampling Techniques » Stratified Random Sampling

Appeared in Year: 2010

### Write in Short

What is PPS Sampling? Explain why such type of sampling is needed? Describe Lahiri’s method for PPS selection of sample.

## Question number: 7

» Sampling Techniques » Stratified Random Sampling

Appeared in Year: 2012

### Describe in Detail

Discuss the allocation of a sample to different strata in stratified sampling. Explain proportional allocation and hence obtain the variance of mean of a stratified sample under proportional allocation.

### Explanation

For a population consisting of N sampling units it can be divided into k relatively homogeneous sub-groups of sizes, , …, (called as strata) such that N=.

Then a simple random sample of size (i = 1, 2, …, k) is drawn from

## Question number: 8

» Sampling Techniques » Stratified Random Sampling

Appeared in Year: 2013

### Describe in Detail

Describe the principles of stratification. Explain how the allocation of sample size in different strata is made.

### Explanation

**Principles of stratification: **

The principle of stratification is the division of the population in such a way that the elements within a stratum are as similar as possible and the means of the strata are as different as possible.

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