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Definition
| the total collection of objects, events, or organisms that have (or could have) a score value for some attribute |
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| a subset of a population (e.g. random, stratified) |
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| Uppercase letters (e.g., X, Y, Z); subscripts to identify specific observations (e.g., X3 for the third observation on X) |
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| manipulated by the experimenter |
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| behavior of participant measured by the experimenter |
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| the measurements that are made on the subjects of an experiment |
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| a number calculated on sample data that quantifies a characteristic of the sample |
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| a number calculated on population data that quantifies a characteristic of the population |
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| methods to organize and summarize data (e.g. monthly sales, batting average, correlation between SAT and GPA) |
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| drawing inferences about a population on the basis of a sample |
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| nominal scale (no properties; ex. Sex: 1 = male, 2 = female...); ordinal scale (magnitude; ex. Class rank: 1st, 2nd, 3rd…); interval scale (magnitude, equal intervals; ex. Degrees F and degrees C); ratio scale (magnitude, equal intervals, and absolute zero; ex. Time, weight, length) |
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Definition
| the lowest and highest score values in a class interval |
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| one half of a measurement unit above and below the apparent limits |
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| halfway point between the lower and upper apparent limits |
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| lower apparent limits are evenly divisible by this number |
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| must not be too many or they will be too complex, or too few because it will be too simple |
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Definition
| the score (X) at or below which a certain percentage of the cases fall |
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Definition
| a value indicating the percentage of cases falling at or below a given score |
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Definition
Raw data: add the scores and divide by N
Grouped data: multiply each midpoint by f, add up each f X and divide by N
Properties:
Σ (X – ) = 0
Σ (X – )2 is at a minimum
Sensitive to all scores in the distribution
Stable with regard to sampling fluctuations |
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Term
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Definition
Raw data: put them in order and find the one in the middle (odd N) or the average of two in the middle (even N)
Grouped data: calculate X50 |
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Definition
Raw data: easy, just count them, more than one mode is possible
Grouped data: the midpoint(s) of the interval(s) with the largest frequency (f) |
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| the degree to which a distribution departs from symmetry about its mean value |
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| mean for a population parameter |
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| standard deviation of a population parameter |
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| variance for a population parameter |
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| standard deviation for a sample statistic |
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| variance for a sample statistic |
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| mean for a sample statistic or unbiased estimator |
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| standard deviation for an unbiased estimator |
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| variance for an unbiased estimator |
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| a sample statistic that in the long run neither overestimates not underestimates its corresponding population parameter |
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| sum of deviations from the mean (always equals 0) |
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