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SimSam is a program to simulate a survey. If you carry out a survey, you select a sample from a population. Then you use the sample data to estimate characteristics of the population. SimSam is a program to simulate samples from finite populations. The program assumes the objective of the sample selection to be estimation of the population mean of a variable.
SimSam simulates samples from a populations. By repeating the selection of the sample a large number of times, and computing an estimate for the population mean for each sample, the distribution of the estimate can be portrayed on the screen. By taking a look at this distribution, it becomes clear how well an estimation procedure is able to estimate the population mean.
Two types of sample designs can be simulated:
- Simple random samples without replacement, and with equal probabilities.
- Samples with replacement, and with probabilities proportional to the values of some auxiliary variable.
Four different estimators can be computed:
- The simple sample mean.
- The ratio estimator.
- The regression estimator
- The post-stratification estimator
To study the effects of nonresponse on an estimator, it is possible to generate nonresponse in the samples.
The result of a simulation is displayed on the screen in the form of a histogram of the distribution of the estimates. This histogram can be saved in a bitmap file for use in other applications.
You can also analyse the distribtion of the estimator by drawing confidence intervals for each sample:
You can ask the program to produce a numerical summary with theoretical and simulated means and standard errors:
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