Chapter 5 Flashcards
Legitimate values of r is between
-1 and 1
What is correlation coefficient
A quantities assessment of the strength and direction of the linear relation between bi arise quantitive data
If correlation coefficient is zero
r=0 what does it mean
Means no correlation
If correlation coefficient is between zero and .5
Means
It is a weak correlation
I correlation coefficient is between point .5 and .8 it means
There is a moderate relation ship
If correlation coefficient is between.8-1
It means
It has a strong relationship
Correlation does not imply
Causation
To interpret correlation coefficient you use
Strength (none, weak, moderate, strong) Direction (negative, positive) Linear reflation ship Between X and Y
What is a residual
Vertical deviation between observation and regression line
Sum of the residuals equal
Zero
Residuals equals
Observed (Y) - expected ( Y hat)
If there is a pattern on a residual graph it means
It is not linear
If a residual graph is random with no pattern it means
That the graph is linear
What is r squared?
It is the coefficient of determination
What is the coefficient of determination?
It is r squared
Interpretation of r^2
Approximately r^2 % of the variation in y can be explained by the LSRL of x and y
What is an influential point
A point that influences where the LSRL is located
What happens I the influential point of a graph is removed?
It will significantly change the slope of the LSRL
Is LSRL effected by an outlier
Yes
Is correlation coefficient r resistant to outliers?
No
Is the coefficient of determination effected by an outlier
Yes
Least squares regression line LSRL is
A line that gives the line of best fit and it minimizes the sum of the squares of deviation from the line
Slope interpretation
For each unit intense in x there is an approximate increase/decreases of b in y
What happens to r ( the correlation coefficient ) when you do anything to the variables?
R the coefficient correlation does not change
