STAT 2040 Lecture Notes - Lecture 2: Time Series, Test Statistic, Null Hypothesis
16 Jan 2017
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Deviation: the difference between an observation and the sample mean. Variance: the average of squared deviations from the mean. Measure the deviation of each observation from this mean. Square these values (to get rid of negatives) Average these squared values **when averaging add the values together but then divide by the degrees of freedom (n-1) rather than the number of values (n)** Standard deviation (s): the square root of the variance. Coefficient of variation (cv): espresses standard deviation as a percentage of the mean. Used when comparing samples measured in different units. Statistics (estimates based on sample): y(bar) = mean of sample s = standard deviation of sample. *since we ususally can"t measure all of a population these values are unknown and are estimated based on and * Distribution: the pattern/ arrangement of values within a set of data, and the frequency of each value.
