1. RANDOM STRATIFIED SAMPLE
Stage 1: Identify those characteristics which appear in the wider population which must also appear in the sample, i.e. divide the wider population into mutually exclusive homogeneous groups.
Stage 2: Randomly sample within these groups, the size of each group being determined by judgement or tables of sample size.

2. THE PROBLEM OF STRATA N S Total Whole company 1,000 278 278
English employees
Scottish employees
Welsh employees
American employees
428

3. SCHOOLING
SUB-TOTAL
SAMPLE SIZE
No schooling
35,020
380
Pre-primary
6,811
364
Primary incomplete
80,285
384
Primary complete
109,561
Junior secondary
94,491
Senior secondary
66,250
382
Tertiary, non-degree
7,481
367
Tertiary, degree
23,944
379
Special
360
186
Total
424,203
3,210
BUT Total without strata
384

4. PROBLEMS OF STRATA
The greater the number of strata, the larger the sample will be.
Therefore, keep to as few strata as necessary.