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20 Cards in this Set
- Front
- Back
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Standard Deviation
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How far away numbers on a liswt are from their average
Steps: 1. Find the Average of the list 2. Subtract the average from each entry 3. Square each Number and Devide by the number of terms 4. Square Root |
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Changing SD
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The SD does not change when something is added or subtracted from the list
The SD is multiplied by the number as is the list changing it by that The closer the numbers are group the 0 the smaller the deviation |
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Median
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Put the list of numbers in order and find the middle number
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Right Hand Tail
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The Average is Larger than the Median
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Left Hand Tail
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The Average is Smaller than the Median
Ex Death Due to Natural Causes |
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Correlation Coefficient
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a measure of how well trends in the predicted values follow trends in past actual values. It is a measure of how well the predicted values from a forecast model "fit" with the real-life data.
It is a number between 1 and -1; the higher is is the better the correlation Doesnt change if you add/multiply |
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Slope of the SD line
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SDy / SDx ( times coeficcient)
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Finding the Correlation Coeficient
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1. Change the x and y values to standard units
2. Multiply the x value by the corresponding y value 3. Average the Product |
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RMSE
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= sqrt(1-r^2) * SD of Y
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Expected Value (w/ Replacement)
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n * average of the box
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Standard Error
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sqrt of n * sd of the box
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SE %
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SD/ sqrt n
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SE for the Average
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SD / sqrt n
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Test of Significance
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Was it due to change? Or something else involves the null and alternative
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z for null questions
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obs-expected/ SE sum
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SE sum
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n * SD
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area percent between 100 and 200
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A= 1/2 ( 100 * 200)
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t-statistic
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obs-exp/ SE
SD unknown smaller sample than 25 1. First compute the SD sqrt (n/n-1) 2. SD+ average is SD+/sqrt n then reg fromula |
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z- statistic
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used in counting
obs-exp/ SE sum |
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box model
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things must be randomly selected
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