POLI 380 Lecture Notes - Lecture 18: Standard Deviation, Central Tendency
Document Summary
One problem with histogram is that we have to choose how many blocks or bars (bins) to use in the graph. Changing the number of binds we use doesn"t alter the data but it can change how we perceive the shape of the distribution. Mean, median and mode are all statistics that help us summarize our data. They are each different indicators of the central tendency of a distribution of a variable. Standard deviation is statistical calculation to summarize the variance of a distribution. Standard deviation is just the square root of the variance. Large deviation has a big impact on statistics. The number itself has no natural meaning, it has meaning only relative to the mean itself and to other standard deviations. When we calculate the variance and sd from sample of data, we technically have to do the calculation with a denominator that is the number of cases minus one.
