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20 Cards in this Set

  • Front
  • Back
Standard Deviation
How far away numbers on a liswt are from their average
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
Changing SD
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
Put the list of numbers in order and find the middle number
Right Hand Tail
The Average is Larger than the Median
Left Hand Tail
The Average is Smaller than the Median

Ex Death Due to Natural Causes
Correlation Coefficient
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
Slope of the SD line
SDy / SDx ( times coeficcient)
Finding the Correlation Coeficient
1. Change the x and y values to standard units
2. Multiply the x value by the corresponding y value
3. Average the Product
= sqrt(1-r^2) * SD of Y
Expected Value (w/ Replacement)
n * average of the box
Standard Error
sqrt of n * sd of the box
SE %
SD/ sqrt n
SE for the Average
SD / sqrt n
Test of Significance
Was it due to change? Or something else involves the null and alternative
z for null questions
obs-expected/ SE sum
SE sum
n * SD
area percent between 100 and 200
A= 1/2 ( 100 * 200)
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
z- statistic
used in counting
obs-exp/ SE sum
box model
things must be randomly selected