chapter6randomerror(參考版)
2025-07-18 18:06本頁面
【正文】 when x ? =2?, z is equal to two。 often, they must be modified substantially when applied to a small sample because a few data points may not be representative of the population. The Population Mean ? and the Sample Mean x Statisticians find it useful to differentiate between a sample mean and a population mean. The sample mean x is the mean of a limited sample drawn from a population of data. It is defined by The population mean ?, in contrast, is the true mean for the population. In the absence of any systematic error, the population mean is the true value for the measured quantity. xxNiiN , w h e n N i s sm a l l? ??1? , w h e n N ? ? ??? xNiiN1…continued… To emphasize the difference between the two means, the sample mean is symbolized by x and the population mean by ?. When N is small, x differs from ? because a small sample of data does not exactly represent its population. The probable difference between x and ? decreases rapidly as the number of measurements making up the sample increases。 (3) temperature fluctuations, which affect the volume of the pipet, the viscosity of the liquid, and the performance of the balance。Chapter 6 Random Error The Nature of Random Errors Random, or indeterminate, errors occur whenever a measurement is made. This type of error is caused by the many uncontrollable variables that are an inevitable part of every physical or chemical measurement. There are many contributors to random error, but often we cannot positively identify or measure them because they are small enough t
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