95fejlmargin

95fejlmargin is a statistical term used in Danish reporting to denote the margin of error associated with a 95 percent confidence interval in estimates derived from samples. It describes how much an observed estimate is expected to vary from the true population value due to random sampling.

Calculation for proportions: e = z sqrt(p(1-p)/n) multiplied by the finite population correction if relevant, where z is the critical value for 95% confidence (approximately 1.96), p is the estimated proportion, and n is the sample size. If p is unknown, using p = 0.5 gives the most conservative (largest) margin. For means, e = z s / sqrt(n), where s is the sample standard deviation, again with a finite population correction if applicable.

Finite population correction (FPC) can reduce the margin when the sample size is a substantial fraction of the population. Example: a poll of 1,000 people estimating a proportion near 0.5 with a large population and p = 0.5 yields roughly e ≈ 1.96 sqrt(0.25/1000) ≈ 0.031, i.e., about ±3.1 percentage points.

Interpretation: A 95fejlmargin of ±3 percentage points means there is approximately 95% confidence that the true population proportion lies within the range estimate ±3 percentage points, assuming the sampling method is random and free from major biases.

Limitations: The margin of error only reflects random sampling error and does not account for systematic biases, nonresponse, weighting, or measurement errors. It is commonly reported in public opinion polls and market research to convey precision.

See also: confidence interval, sampling error, sample size, finite population correction.

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