PSYC2203 Chapter Notes - Chapter 3: Squared Deviations From The Mean, Interquartile Range, Standard Deviation
Document Summary
Chapter 3: measures of variability: measures of central tendency vs. Measures of variability: measures of central tendency (e. g. , mean, median, mode) provide useful, but limited information. Information is insufficient in regards to the dispersion (i. e. , variability) of scores of a distribution: three measures of variability that researchers typically examine: range, variance, and standard deviation. Standard deviation is the most informative and widely used of the three. Why not go straight to standard deviation: we need to calculate the variance before finding the standard deviation. That is because we need to square the deviation scores so they will not sum to zero. N: formulas for calculating the variance and the standard deviation are virtually identical. There are other formulas (e. g. , raw score formula). Differences between the sample and population formulas: why n 1: if population mean is unknown, use the sample mean as an estimate.
