## Stratified sample size - sampling size, Operation Research

Assignment Help:

Stratified Sample Size

The  sampling  study  has depended  much on the stratified sample  to reduce  the sampling  error, samples  size may have a number of strata or  clusters. The researcher   will have  to deal within  strata variability and within and between cluster variability in calculating the sample size. Since allocation of  the population members into  strata confines  each sub  samples  variance within the range of values in  each stratum the sampling error is  reduced to a very  nominal level the standard error has a  determined affect on the sample size. The stratified sample  size may  be  proportional of  disproportional. While  one stratum  may contain 0.55% of the  population size the other may contain  0.08% , 0.10% so on. The  percentage  may very as per requirements  and situations. In case of  stratified sampling only  the size  of the strum is used  as guide for allocating  the total  sample. The  size of stratified sampling may be  calculated as below :

Ni = Ni /N -n

Where

n = Number  of sample units  from stratum

Ni = total number  of units in  stratum

N= total number  of units  the population

n = sample  size  desired

the  advantage  of proportional  allocation  is that  it leads to an  estimate which is  computationally  simple. For calculation the  weighted  estimates, the  weighted calculation  of each  stratum is totalled.

Thus  standard  deviation of all the

x st= √∑W3  ∑  i 2 / ni

Where  W i = weight of  stratum i = Ni/N

standard  deviation of the i stratum

The  disproportional stratified sample  may be a more desirable method if the standard deviation of the  observation in  each stratum  is known. Thus the standard  deviation of the mean of a disproportionate  stratified sample.

σ =  σ √ ( W )2 / n

The cost per  observation  did not  enter  into the  formula for calculating the  sample  size  although cost  exerts a direct  impact. If the cost  per observation  or variability  is not  the same  for each  stratum there  is need  of determining  sample size by  considering  the precisions. Cost per  observation  b subgroup  is considered for  calculation  of sample  size.

#### Operations research approach to problem solving, Formulation of the Problem...

Formulation of the Problem: Before proceeding to find the solution of a problem, first of all a manager should be competent enough to form an appropriate model. To do so f

#### Significance and scpope of o.r, significance and scope of operation resarch...

significance and scope of operation resarch in morden management?

#### MB0048, A paper mill produces two grades of paper viz., X and Y. Because of...

A paper mill produces two grades of paper viz., X and Y. Because of raw material restrictions, it cannot produce more than 400 tons of grade X paper and 300 tons of grade Y paper i

#### Linear pograming, application area of linear programing problem

application area of linear programing problem

#### Application of the chi square test - hypothesis testing, Application of the...

Application of the chi Square Test   The  chi square distribution  has a number of applications are given  below: a.Chi Square test of goodness of fit. b.Chi square te

#### Degree of correlation ship - correlation regression analysi, Degree of  Co...

Degree of  Correlation ship 1. Perfect Correlation: When  changes  in  two related variables are  exactly  proportional  there is  perfect correlation between  them. In case

#### Models, what is similation model as a type of mathematical models

what is similation model as a type of mathematical models

#### General rules, General Rules a. Attractive Shapes The tables  should ...

General Rules a. Attractive Shapes The tables  should be  neat  and  attractive. The size of  table  should be neither too big nor  small. b. Simplicity A table  should b

#### Demerits - correlation regression analysis, Demerits a.It cannot  be ...

Demerits a.It cannot  be used in  the case  of  bi variate distribution. b.If the  numbers  of items  are greater than say  30, the calculation becomes  tedious  and  requ

#### Describe the problems of operation management, describe the problems of ope...

describe the problems of operation management