How do you find variance in stratified random sampling?
The stratified sample mean, st, is given by the weighted average of the sample means of the characteristic of interest from each stratum, and the stratified sample variance is simply the sum of the variances within each stratum.
How do you calculate stratified sampling?
For example, if the researcher wanted a sample of 50,000 graduates using age range, the proportionate stratified random sample will be obtained using this formula: (sample size/population size) x stratum size.
How do you calculate strata size?
The strata size is the number of people in each group, 12, 34, 48, 21 and 3 in this example. The total number of customers = 12 + 34 + 48 + 21 + 3 = 118.
What is Slovins formula?
Slovin’s formula. – is used to calculate the sample size (n) given the population size (N) and a margin of error (e). – it’s a random sampling technique formula to estimate sampling size. -It is computed as n = N / (1+Ne2).
What is stratified proportionate sampling?
Proportionate stratified sample means that size of sample strata is proportional to the size of population strata; in other words, probability of unit being selected from the stratum is proportional to relative size of that stratum in population.
What is stratified sampling in maths?
Stratified Sampling This is where we divide the population into groups by some characteristic such as age or occupation or gender. Then make sure our survey includes people from each group in proportion to how many there are in the whole population.
What is stratified probability sampling?
Stratified random sampling is a type of probability sampling using which a research organization can branch off the entire population into multiple non-overlapping, homogeneous groups (strata) and randomly choose final members from the various strata for research which reduces cost and improves efficiency.
What is the difference between N and N in Slovins formula?
Where: n = Number of samples, N = Total population and.
Why do we use Yamane formula?
Yamane (1967:886) provides a simplified formula to calculate sample sizes. This formula was used to calculate the sample sizes in Tables 2 and 3 and is shown below.
Why do you calculate variance?
Variance is a measurement of the spread between numbers in a data set. Investors use variance to see how much risk an investment carries and whether it will be profitable. Variance is also used to compare the relative performance of each asset in a portfolio to achieve the best asset allocation.
What is math variance?
The variance is the average of the squared differences from the mean. For example, if a group of numbers ranges from 1 to 10, it will have a mean of 5.5. If you square the differences between each number and the mean, and then find their sum, the result is 82.5.