The ABI is a stratified random sample, using SIC92/ 2003, employment and country as stratifying variables.
As in all samples the estimates from the survey are subject to various sources of error. The total error in a survey estimate is the difference between the estimate derived from the data collected and the true (unknown) value for the population. The total error consists of two main elements; the sampling error and the non-sampling error.
The ABI was designed to minimise both these errors.
Sampling error
The sampling error is the error that arises because the estimate is based on a survey rather than a census of the population. The results obtained for any single sample may, by chance, vary from the true values for the population but the variation would be expected to average to zero over a number of repeats of the survey.
The standard error is the estimated value of the sampling error. Our estimate for a variable, plus and minus the standard error for the variable, gives a range in which the true unknown value for the population should lie. The closer the standard error to 0, the more reliable the estimate.
The coefficient of variation is the standard error of a variable divided by the survey estimate, and it is used to compare the relative precision across surveys or variables. The closer the coefficient of variation is to 0, the more reliable the estimate.
Sampling errors for ABI surveys are available at 3 digit SIC92/ 2003 group level for the following variables:
Total Turnover
Approximate Gross Value Added at Basic Prices
Total Purchases of Goods and Services
Total Net Capital Expenditure
Non-sampling error
Non-sampling errors are not easy to quantify and include inadequate coverage, measurement, processing and non-response.
The response rate gives an indication of the likely impact of non-response error on the survey estimates.
Introduction to ABI
