Page 70 - DMGT404 RESEARCH_METHODOLOGY

Research Methodology

Notes Third step - Determine how many are to be selected from marketing stream (say n1)
n = 30 × 1/10 = 30 × 1/10
1
Sample to be selected from marketing strata n = 30 × 1/10 = 3
1
Now we can select 3 numbers from among 30 numbers at random say 7, 60, 22

Similarly we can select n n
2 3
n = 20 × 1/10 = 2
2
The 2 numbers selected at random from finance stream are 13, 59
N = 10 × 1/10 = 1
3
Stratified sampling can be carried out with:
1. Same proportion across the strata proportionate stratified sample.
2. Varying proportion across the strata disproportionate stratified sample.

Example:
Size of stores No. of stores Sample Sample
(Population) Proportionate Disproportionate
Large 2,000 20 25
Medium 3,000 30 35
Small 5,000 50 40
10,000 100 100

Estimation of universe mean with a stratified sample

Example:

Size of stores Sample Mean No. of stores Percent of stores
Sales per store
Large 200 2000 20
Medium 80 3000 30
Small 40 5000 50
10,000 100

The population mean of monthly sales is calculated by multiplying the sample mean by its
relative weight.
200 × 0.2 + 80 × 0.3 + 40 × 0.5 = 84

Sample Proportionate

If N is the size of the population.
n is the size of the sample.

i represents 1, 2, 3,…………..k [number of strata in the population]
\ Proportionate sampling

64 LOVELY PROFESSIONAL UNIVERSITY