chapter6randomerror(文件)
【正文】 visual judgments, such as the level of the water with respect to the marking on the pipet and the mercury level in the thermometer。 and (4) vibrations and drafts that cause small variations in the balance readings. Undoubtedly, numerous other sources of random uncertainty also operate in this calibration process. It is difficult or impossible to determine the influence of any one of the random errors arising from these variables, but the cumulative effect is responsible for the scatter of data points around the mean. Results of coin flipping Normal error curves Samples and Populations A finite number of experimental observations is called a sample of data. The sample is treated as a tiny fraction of an infinite number of observations that could in principle be made given infinite time. Statisticians call the theoretical infinite number of data a population, or a universe, of data. Statistical laws have been derived assuming a population of data。 and so forth. A plot of relative frequency versus this parameter yields a single Gaussian curve that describes all populations of data regardless of standard deviation. The square of the standard deviation is called the variance. A normal error curve has several general properties: (1) The mean occurs at the central point of maximum frequency
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