hi
I need to conduct survey of school in a district with 7 sub divisions (tehsils). the number of schools for girls and boys varies across each tehsil based on the population of the city. the enrollment of students in each school is missing but enrollment at district level is known. I need to conduct 2 step stratified random sampling. what should be the total sample size for the district or sub divisions.
once the sample size is decided i can divide it across each tehsil based on proportional sampling.
i need to measure student's abilities.
Hi Andleeb,
Here are a couple of links that may be helpful:
https://books.google.com/books?id=WBSwhw-j1ZoC&printsec=frontcover&dq=%22sample+size%22+statistics&hl=en&sa=X&ved=0ahUKEwiCuu7hr6_bAhVQ7FMKHZTaAysQuwUILDAA#v=onepage&q=%22sample%20size%22%20statistics&f=false
https://books.google.com/books?id=3uqZ_81If4UC&printsec=frontcover&dq=%22sample+size%22+statistics&hl=en&sa=X&ved=0ahUKEwiCuu7hr6_bAhVQ7FMKHZTaAysQuwUIODAC#v=onepage&q=%22sample%20size%22%20statistics&f=false
Have a great day!
---Adrian
Hi Ms.Ismail
In order to select a suitable sample and to answer this question/problem, several remarks have to be studied.
1. General remarks:
Research studies are usually carried out on sample of subjects rather than whole populations. The most challenging aspect of fieldwork is drawing a random sample from the target population to which the results of the study would be generalized. The key to a good sample is that it has to be typical of the population from which it is drawn. When the information from a sample is not typical of that in the population in a systematic way, we say that error has occurred. In actual practice, the task is so difficult that several types of errors, i.e. sampling error, non-sampling error, Response error, Processing error,…
2. In addition, the most important error is the Sampling error, which is statistically defined as the error caused by observing a sample instead of the whole population. The underlying principle that must be followed if we are to have any hope of making inferences from a sample to a population is that the sample be representative of that population. A key way of achieving this is through the use of “randomization”.
3.There several types of random samples, Some of which are: Simple Random Sampling, Stratified Random Sampling, Double-stage Random Sampling... Moreover, the most important sample is the simple random sample which is a sample selected in such a way that every possible sample of the same size is equally likely to be chosen. In order to reduce the sampling error, the simple random sample technique and a large sample size have to be developed.
4. Specific remarks:
The following factors are highly affected the sample size and need to be identified:
- Population Size,
- Margin of Error,
- Confidence Level (level of significance) and
- Standard of Deviation.
5. Finally, the sample size can be estimated by,
Necessary Sample Size = (z-score or t-value)2 * StdDev*(1-StdDev) / (margin of error)2 .
Regards,
Zuhair
For more details, please refer to
Cochran,W.G. (1977). Sampling techniques, Wiley.
Snedecor, W.G. and Cochran,W.G. (1989). Statistical Methods, Blackwell.
Regards,
Zuhair
Hi Andleeb,
Here are a couple of links that may be helpful:
https://books.google.com/books?id=WBSwhw-j1ZoC&printsec=frontcover&dq=%22sample+size%22+statistics&hl=en&sa=X&ved=0ahUKEwiCuu7hr6_bAhVQ7FMKHZTaAysQuwUILDAA#v=onepage&q=%22sample%20size%22%20statistics&f=false
https://books.google.com/books?id=3uqZ_81If4UC&printsec=frontcover&dq=%22sample+size%22+statistics&hl=en&sa=X&ved=0ahUKEwiCuu7hr6_bAhVQ7FMKHZTaAysQuwUIODAC#v=onepage&q=%22sample%20size%22%20statistics&f=false
Have a great day!
---Adrian
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