Modules 56 57 Module 56 Descriptive Statistics 01 24 2012 Statistics the branch of mathematics concerned with collecting organizing analyzing and drawing conclusions from numerical data Descriptive statistics the branch of statistics that provides a means of summarizing data Frequency distribution an arrangement of scores from a sample that indicates how often a particular score is present Histogram bar graph Central tendency is an index of the central location within a distribution of scores the mean median and mode Mean the average the sum of all scores divided by the number of scores Median the point in a distribution of scores that divides the distribution exactly in half when the scores are listed in numerical order Mode the most frequently occurring score in a set of scores Normal distribution a distribution of scores that produces a symmetrical bell shaped curve in which the right half mirrors the left half and in which the mean median and mode all have the same value Module 57 Measures of Variability Variability the spread or dispersion of scores in a distribution Range the difference between the highest score and the lowest score in a distribution Standard deviation an index of the average deviation of a set of scores from the center of the distribution 1 Calculate the mean 2 Subtract the mean from the original score 3 Deviation score is squared 4 Add all the squared deviation scores and divide by the number of scores 5 Take the square root 01 24 2012 01 24 2012
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