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measures of central tendency such as ________________________________ summarize a distribution of scores by describing the most common, the middle score, or the average score of the distribution
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central purpose of descriptive statistics is to __________________ data
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Statistics
Chapter 3 & 4
| Question | Answer |
|---|---|
| measures of central tendency such as ________________________________ summarize a distribution of scores by describing the most common, the middle score, or the average score of the distribution | mode, median, and mean |
| central purpose of descriptive statistics is to __________________ data | summarize or reduce |
| always the exact center of a distribution of scores | mode |
| median can be found for _______________ data, but generally it more appropriate for ______________ data. | interval ratio; ordinal |
| ______________identifies a point below which a specific percentage of cases fall | percentile |
| the 5th decile, is equal to the ________ percentile | 50th |
| D1 or the first decile is the point below which ______________ of the cases fall | 10% |
| If you scored higher than the 3rd quartile (Q3) then you made __________________________ | above 75% of the scores |
| most commonly used measure of central tendency | mean (x bar) |
| formula for mean (x bar)= | the sum of (xi) / N |
| three characteristics of the mean: | 1. the mean balances out all scores (mean is pt around which all scores cancel out); 2. mean minimizes variation of scores (least squares principle); 3. mean affected by all scores and can be misleading if distribution has extreme outliers |
| what does least square principle say? | mean is pt around which variation of score is minimized; if difference b/t scores and mean are squared and then added, the resultant sum will be less than the sum of the squared differences b/t the scores and any other point in the distribution |
| This principle underlies the fact that the mean is closer to all of the scores than the other measures of central tendency | least squares principle |
| distributions with outliers have a ___________: | skew |
| if you have some extremely high outliers, what will happen to the distribution curve? | it will skew to the right (+) = (mean>median) |
| when mean > median, what would you expect your distribution curve to look like? | skewed to the right (+ skew) |
| if you have some extremely low outliers, what will happen to the distribution curve? | it will skew to the L (-) = mean< median |
| if mean < median, what would you expect your distribution curve to look like? | skewed to the left (- skew) |
| the mean will be pulled _______________ of the outlying scores relative to the median | in the direction |
| the greater the skew, the ______________ the difference between the 2 measures of central tendency (mean & median) | greater |
| the mean and median will have the same value only in distributions that are ________________- | symmetrical |
| the mode is the most ___________________ and is used most appropriately with _____________________variables | common value; nominal-level |
| _____________ describe the variety, diversity, or heterogeneity of a distribution of scores; describes the variability of data (variants.) | measures of dispersion |
| measure of dispersion can reveal substantial differences between distributions even when _____________________ are the same | measures of central tendency |
| range: | distance between highest and lowest scores in distribution (high score-low score) |
| the greater the value of a range the greater the _______________ in the distribution | dispersion |
| limitations to range | range might exaggerate the amount of dispersion for most of scores in distribution |
| IQR: | the distance from the third to 1st quartile; a kind of range that acoids some of the problems associated with range outliers by considering only the middle 50% of the cases in distribution |
| three traits a good measure of dispersion should include: | should use all the scores in the dist; should describe the average or typical deviation of the scores; increase in value as the scores become more diverse |
| the sum of squared deviations will _______________ with sample size | increase |
| using the median, range and IQR depicts both the _______________ and _____________________- | central tendency; variability |
| horizontal line in the middle of the IQR box represents : | median |
| scores that are beyond 3 times the height of the IQR box in either direction are termed: | extreme outliers (outliers are outside of 1.5 height of box or outside the whiskers) |
| the standard deviation is ____________ for more diverse distributions and ______________ for less diverse distributions | higher; lower |
| sigma of x-sub-I = | the sum of all data points |
| t/f data that has a mean of 30 and a range of zero means there is littler variance | false - no variance |
| if you take all data points in a sample and find the difference between the mean and the sum, the answer will always be? | 0 |
| the sum of x sub i - x bar = | 0 |
| limitations to mean: | outliers (extreme values) skew the mean |
Created by:
aereal