In statistics, when analyzing collected data, the samples observed differ in such things as means and standard deviations from the population from which the sample is taken. This is sampling error and is controlled by ensuring that, as much as possible, the samples taken have no systematic characteristics and are a true random sample from all possible samples. If the observations are a true random sample, statistics can make probability estimates of the sampling error and allow the researcher to estimate what further experiments are necessary to minimize it. Statistics is a type of data analysis which includes the planning, summarizing, and interpreting of observations of a system possibly followed by predicting or forecasting of future events based on a mathematical model of the system being observed. ... DATA (Debt, AIDS, Trade, Africa) was established in 2002 by Bono (Paul Hewson) of the Rock band U2, and Bobby Shriver, along with activists from the Jubilee 2000 Drop the Debt Campaign, as an organisaton focused on Justice, not charity. ... A sample is that part of a population which is actually observed. ... It has been suggested that this article or section be merged with Simple random sample. ... For the railroad use of the term observation, see observation car. ... It has been suggested that this article or section be merged with Simple random sample. ... Statistics is a type of data analysis which includes the planning, summarizing, and interpreting of observations of a system possibly followed by predicting or forecasting of future events based on a mathematical model of the system being observed. ... The word probability derives from the Latin probare (to prove, or to test). ...
Samplingerror of a mean value estimated from a sample is equal to the estimated standard deviation of the variable divided by the square root of the sample size.
If we have computed a sample mean of household size of 2.6 and we determine that the samplingerror on this value 0.01, then this means that we have 95 percent confidence that the estimated value of 2.6 is within 0.02 of the population value.
Because samplingerror is a function of the method used to draw the sample, extracting subsets of the data may have the effect of invalidating the error estimation, if the subsets are drawn in such a way as to introduce a substantial non-random element into the subset.
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