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15 Cards in this Set
- Front
- Back
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X= |
Random variable. Represents sample data collected (e.g., age of patient at time of first disease diagnosis, patient blood pressure) |
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Sub-indices (Xi) |
Sub-index i represents ith observation of variable in the sample N is total number of observations for a variable, so sub-index i can take values from 1,2,3,...n |
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Summation (Σ) |
Represents sum of a group of values of a variable |
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Mean (X and μ)
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X=sample average of data collected. μ=population average is unknown |
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Standard deviation (s and σ)
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Measure of variable dispersion (e.g., average dispersion about he mean) s = sample standard deviation (SD) σ= population SD Variance= s 2(sample) & σ 2 (population) |
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Graphical view
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Histograms, Bar Charts, Stem & Leaf Plots,. |
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Numerical view
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Mean, Median, Mode, Standard Deviation, |
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Mean:
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What is the average level of the data observed? |
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Mode
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: What is the most likely value of the data observed? |
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Median:
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What is the level with half of the observations being less than that level? |
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Range
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What is the difference of the extremes in the possible values observed in the data? |
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Standard Deviation, Interquartile, Range & Variance |
What is the variability of the data? |
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Variance intuition |
It is “average” of the squared distances with respect to the mean |
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Standard deviation intuition: |
It is the square root of the variance intuition, so it is an approximate “average” absolute distances to the mean |
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Skewness |
Skewness refers to the symmetry of the data. The long tail reflects where the skewness is happening (left skewness vs right skewness) |
