When you want to size the sample size, the procedure proceeds in three distinct steps:
1. Evaluate the data collection instrument and judge the most important variable of the questionnaire or the most significant group of variables;
2. Analyze if it is ordinal, interval or nominal;
3. Check if the population is finite or infinite;
Interval variable and infinite population
Interval variable and finite population
Nominal or ordinal variable and infinite population
Nominal or ordinal variable and finite population
Note: The proportion (p) will be the estimate of the true proportion of one of the chosen levels for the adopted variable. For example, 60% of the sample phones is Nokia, so p will be 0.60.
The ratio (q) will always be 1 - p. In this example q, will be 0.4. The error is represented by d.
For cases where the proportions cannot be identified, 0.5 is given for p and q.Next: Data Types