Steekproefproportie en populatieproportie

In a global survey, a researcher found that 8500 out of 10,000 respondents suggested legally protecting the rain forest.

It is impossible to receive responses from everyone in the global population. So, these 10,000 responses can be utilized for analysis, what is called a sample, drawn from the population.

The ratio 8500 divided by 10,000—the proportion of people suggesting legal protection of rainforests—gives us a value 0.85, or 85%, which is called a sample proportion, denoted as .

Assuming that the sample of 10,000 individuals accurately represents the whole population, the sample proportion can be used to estimate the population proportion, denoted as .

The single value obtained from such a sample is then called the point estimate. In this case, the sample proportion 0.85, or 85% is the point estimate of the population proportion.

Multiple such sample proportions can be obtained by conducting the survey repeatedly to determine if a point estimate is unbiased. It is considered unbiased when the standard deviation around it is small.