Stratified random sampling, Applied Statistics

Assignment Help:

Stratified Random Sampling:

This method of sampling is used when the population is comprised of natural subdivision of units, The method consist in classifying the population units into a certain numbers of groups called strata. Then random samples are selected   independently from each group. The division of the population into strata is done in such a way that.

(1)   There is greater homogeneity within each group also  called stratum;

(2)   There is no over lapping in various strata or groups.

In practice geographical, sociological and economic characteristics are used for dividing the universe into different strata.  For example, if is desired to study the wage levels of workers in an industry, it would be better to classify all works into skilled and unskilled males and females categories and then select random simple   from each group  in the ratio to the size of that group  in population. The size of sample from each strata may either be proportional or disproportional to  the size of each.

(a)    Proportional Size: Under this a given percentage of items are selected from each stratum. For example in case of 50% selection there will be a selection of 5 to 10 units and 10 of20 units. Consisting of 10 and 20 units. This selection will be at random following any of the methods discussed earlier.

(b)   Disproportional Size: A disproportional selection may also be followed if different strata reveal different levels of within strata variability. Following the normal sampling rules, a larger sample is recommended if some sub strata reveal greater degree of variability with regard to a phenomenon relevant to the inquiry in comparison to the general lot.


Related Discussions:- Stratified random sampling

Universe or population, Universe or Population The word universe as use...

Universe or Population The word universe as used in statistics denotes the aggregate from which a sample is to be taken. According to Simpson and Kafka, a universe or populatio

Probability distribution and sampling distribution , a 100 squash balls are...

a 100 squash balls are bounce from height of 100 inches with average height 30 inch with standard deviation 3/4 inch. a ball is fast if bounce above 32 inch. what is chance of gett

Box plots, This box plot displays the diversity wfood; the data ranges from...

This box plot displays the diversity wfood; the data ranges from 0.05710 being the minimum value and 0.78900 being the maximum value. The box plot is slightly positively skewed at

Hypothesis testing, the president of a certain firm concerned about the saf...

the president of a certain firm concerned about the safety record of the firms employee sets aside $50 million a year for safety education. the firms accountant believes that more

Determine the maximum weight rounded down, Assume that the pulley at A is a...

Assume that the pulley at A is a small frictionless pulley. The cord AB is only allowed to support a maximum tension in Newtons as given in P4, and the cord supporting the block ca

Local truncation error, (a) If one solves the ordinary differential equati...

(a) If one solves the ordinary differential equation using Euler's method find an expression for the local truncation error. (b) Using the result of (a) above what will

Stk, The mean tax-return preparation fee H&R Block charged retail customers...

The mean tax-return preparation fee H&R Block charged retail customers in 2012 was $183 (The Wall Street Journal, March 7, 2012). Use this price as the population mean and assume t

Eliminate all of the insignificant variables, The file Midterm Data.xls ha...

The file Midterm Data.xls has a tab labeled "Many vs. S&P" which presents historical price data for several assets, a volatility condition (VIDX = 1 if the NYSE volatility is grea

Regression, Regression line drawn as Y=C+1075x, when x was 2, and y was 239...

Regression line drawn as Y=C+1075x, when x was 2, and y was 239, given that y intercept was 11. calculate the residual

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd