Presentation on determination of size of sample (n)
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The document discusses determining the appropriate sample size (n) when selecting representative samples. It states that sample size should be chosen optimally to balance flexibility, efficiency, reliability and representativeness. The formula n = [z.sd/E]2 is presented, where n is the sample size, z is the confidence level, sd is the population standard deviation, and E is the desired error or difference between the sample and population means. The document also notes factors that impact sample size choice like variability of data, nature of stratification, and risk of biased estimates.
![n = [ z. sd / E]²
Where
n = size of sample
z = Value at a specified level of confidence or
desired degree of precision
Sd = Standard deviation of the population.
E = Different between population mean and sample
mean. Or desired error in estimation of pop.
Mean](https://image.slidesharecdn.com/presentationondeterminationofsizeofsamplen-150123040237-conversion-gate01/85/Presentation-on-determination-of-size-of-sample-n-5-320.jpg)
![n = [ z. sd / E]² formula was
derived from E= z × sd/√n
When sample data is collected and the sample
mean is calculated, that sample mean is typically
different from the population mean µ.
This different sample and population mean can be
thought of as an error . The margin error E is the
maximum difference between the observed
sample mean and true value of population mean
µ.](https://image.slidesharecdn.com/presentationondeterminationofsizeofsamplen-150123040237-conversion-gate01/85/Presentation-on-determination-of-size-of-sample-n-6-320.jpg)
Presentation on determination of size of sample (n)
- 1. PRESENTATION ON DETERMINATION OF SIZE OF SAMPLE(n) & CHARACTERISTICS INCLUDED WHILE SELECTING REPRESENTATIVE SAMPLES
- 2. GROUP MEMBERS Nabin jamkatel Rajiv gupta Mohits lama
- 3. Sample size determination is the act of choosing the number of observations or replicates to include in a statistical sample Sample sizes may be chosen in several different ways: • once the sample expedience - For example, include those items readily available or convenient to collect. A choice of small sample sizes, though sometimes necessary, can result in wide confidence intervals or risks of errors in statistical hypothesis testing. • using a target variance for an estimate to be derived from the sample eventually obtained • using a target for the power of a statistical test to be applied is collected
- 4. Large sample may waste time, resources and money. To small sample may lead to inaccurate result So we have concluded that size of sample should be optimum(flexibility, efficiency, reliability and representativeness)
- 5. n = [ z. sd / E]² Where n = size of sample z = Value at a specified level of confidence or desired degree of precision Sd = Standard deviation of the population. E = Different between population mean and sample mean. Or desired error in estimation of pop. Mean
- 6. n = [ z. sd / E]² formula was derived from E= z × sd/√n When sample data is collected and the sample mean is calculated, that sample mean is typically different from the population mean µ. This different sample and population mean can be thought of as an error . The margin error E is the maximum difference between the observed sample mean and true value of population mean µ.
- 7. The reasons and objectives of sampling The relationship between accuracy and precision The reliability of estimates with varying sample size The determination of sample size for surveys The variability of data The nature of stratification and its impact on survey cost The risk posed by biased estimates
- 8. Sampling Accuracy It is usually expressed as a relative index in percentage form and indicated the closeness sample based parameter estimator to the true data population value. Sampling Precision It is related to the variability of the sample used . It is measured by C.V.
- 9. Thank you……