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13 Cards in this Set
- Front
- Back
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Descriptive vs Inferential Statistics
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Descriptive - Procedures that simplify and summarizes data
- Mean, Median, Mode etc Inferential - Hypothesis Testing to determine relationships between variables and making predictions. |
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Internal vs External Validity
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Internal
- Estimate of the degree to which causal inferences can be made. Experiments in highly controlled laboratory settings have better internal validity. External - The extent to which the results can be applied to different people, places, and times. |
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Continuous Variables
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Interval - Arranged in equally spaced units and difference between points can be measured
- No Absolute zero - Temperature Ratio - There is an absolute zero - Magnitude of differences between categories is the same - Age |
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Categorical Variables
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Nominal
- No Natural Order - Gender: Binomial, Race: Polynomial Ordinal - Categories with natural rank or order - Income levels, grades |
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Boxplot
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Max & Min
75th and 25th percentile Median |
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Quantiles
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- Percent of sample points that are less than or equal to it
- Median is 50th percentile - Less sensitive to outliers |
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Calculating Outliers
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Upper outlier: 75th Percentile + 1.5 x IQR
Lower outlier: 25th percentile - 1.5 x IQR Extreme outlier is 3 x IQR |
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Measures of Spread
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Variability
Range, Variance, Standard deviation |
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Normal Distribution Ranges
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1 STD - 68.2%
2 STD - 95.4% 3 STD - 99.7% |
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Confidence Interval
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CI = Mean +/- (1.96 * SE)
SE = SD / Sqrt(n) |
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Error Types
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Type 1 - False Positive
- Reject the null when null is true - alpha is Type 1 error Type 2 - False Negative - Fail to reject Ho when alternate is true - Beta |
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Power
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Probability of rejecting the null given that alternative is true
Power of test = 1 - Beta |
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Using CI to test Null
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If null does not fall between CI - Reject null
If null falls between CI - Fail to reject null |
