CHEM211 Chapter Notes -Gaussian Function, Standard Deviation, Confidence Interval
16 Aug 2015
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Mean - gives center of the distribution (sum of the measured values divdied by n) Stdev - width of the distribution (how closely the data are clustered about the mean) Experiment that produces a small stdev is more precise than large stdev. Greater precision does not necessarily imply greater accuracy. Square of the standard dev is called variance. Standard dev expressed as percentage of the mean value is called relative standard dev (coefficient of variation) Z = x - mean / standard dev. The probability of measuring z in a certain range is equal to the area of that range. A gaussian curve with unit area is called a normal error curve. Confidence interval = sample mean +/- (t) (sample standard dev) / (sqrt (n)) Solutions containing known concentrations of analyte - standard solutions. Solutions containing all reagents and solvents used in the analyte, but no analyte - blank solutions.
