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17 Cards in this Set
- Front
- Back
Independent Variable
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X= predictor= Exposure= independent variable
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Dependent Variable
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Y= outcome= Disease= response variable= dependent variable
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Nominal Variable
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Level of measurement scale.
Data by name alone, no consideration of magnitude or order. Ex- 1= Females 2= Males. Also dichotomous or binomial. Also called categorical Can only be discrete variables |
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Ordinal Variable
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Ordered catagorical variables.
Ordered or ranked categories but not necessarily in magnitude. Ex- 1= Freshman, 2= Sophomores Can be discrete or continuous |
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Continuous Variable
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May take any value. Ex- blood pressure, cholesterol
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Discrete Variables
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Counts.
Data with assigned order and magnitude but restricted to whole numbers. Nominal, ordinal, interval and ratio variables can be discrete |
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Hierarchy of Variables
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A variable can always be analyzed as if it were of a type further down the hierarchy, but not visa versa.
ratio>> interval >> ordinal >> nominal |
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Measures of Central Tendency
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1) Mean
2) Median 3) Mode |
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Measures of Spread
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1) Range
2) Variance 3) Standard Deviation |
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Mean
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Average, unique, simple, includes all numbers, affected by extremes
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Median
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Middle pt of data pts. Unique, simple NOT affected by extreme values.
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Mode
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Most appeared number. Can have none or more than one.
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Range
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Max- Min. Simple,sensitive to extreme values
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Variance
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Variance= SD^2
Uses all data points, always positive. Gives idea of data variability. |
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Standard Deviation
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Is the average deviation of the mean from the observations themselves.
Uses all data points, original units of data. |
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Interval Variable
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Based on variable having intervals of equal length or distance, like inches on a ruler.
Does not have an absolute zero point like ratio scale so total absence of attribute cannot be calibrated. Can be discrete or continuous Ex- Temperature and IQ |
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Ratio Variable
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Based on variable having intervals of equal length or distance, like inches on a ruler.
Does have an absolute zero point. Can be discrete or continous Ex- No. of cigarettes smoked per day |