ADMS 2320 Midterm: Sheet Midterm

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Measures of variability: the observations spread out around the mean value if data are symmetric, with no serious outliers, use range and standard deviation. If comparing variation across two data sets, use coefficient of variation. May be treated as nominal but not interval) Categorical no order nominal (arbitrary numbers represent categories, {pass | fail} Descriptive statistics are methods of organizing, summarizing, and presenting data in a convenient and informative way. Inferential statistics - draw conclusions or inferences about characteristics of populations based on data from a sample. Statistical inference -an estimate, prediction, or decision about a population -based on a sample. Bar charts emphasize frequency of occurrences of the different categories. Use when the order in which nominal data are presented is meaningful. Pie chart emphasize the proportion of occurrences of each category. Histogram is most important graphical method for single set of interval data; it doesn"t only summarize interval data but also help explain probabilities.