Residuals
To find the residual of a data point you should ...
What is subtract predicted from observed/actual?
Residual = Actual - Predicted
Predicted Price = 18.617 + 103.929 * Capacity.
This is the regression equation for disk space Capacity (in megabytes) versus Price (in dollars) at a local store. The slope of 103.929, in this context, means...
What is
for every 1 mb increase in capacity, the price increases by $103.929.
List the steps to find the linear regression equation of a line given a data set in your calculator.
1) Stat, Edit, Enter data in Lists 1 and 2, Quit
2) Stat again, then CALC Linear Regression (4)
or Stat, Test, LinRegTTest (if you want regression equation as well as r and r^2)
In slope intercept form, y=mx+b, this variable represents the y-intercept.
What is
b
Describe a correlation of -0.9 in terms of strength (weak, moderate, or strong) and direction.
What is
very strong, negative (slope of line is negative so line is going downward from left to right).
With an observed value of 25.8 and a predicted value of 45.9, what is the residual?
-20.1
Predicted Price = 18.617 + 103.929 * Capacity.
This is the regression equation for disk space Capacity (in megabytes) versus Price at a local store. With a capacity of 2 mb, the expected price would be...
What is
$226.475
The variable used to represent the correlation coefficient is...
What is
r
The value of r = -0.75 tells us _________ about the linear regression.
What is
it has a fairly strong or moderate, negative correlation (the slope is negative so the line is going downward from left to right)
Sketch a data set with a correlation correlation of 0.98.
Show on paper or whiteboard
True or False: Residuals can be positive or negative
What is
True.
The linear model for a local store's Number of Sales people working versus Sales is as follows: Sales = 8,106 + 91.34n (where n=Number of Sales People Working). In this situation the slope means...
What is
for every increase of 1 sales person working, sales increase by $91.34.
You typed your data into lists L1 and L2.
To find predicted values for your linear regression of your data set, you would then...
What is
in List 3, up in the title bar, enter in the linear regression equation, but instead of x, type in L1 then hit enter
The linear model for a local store's Number of Sales people working versus Sales is as follows:
Sales = 8,106 + 91.34n (where n=# Sales People Working)
The y-intercept is...
What is
$8,106
A restaurant's menu items are compared in terms of correlation. Sugar versus Calories have a correlation of 0.25. Sugar versus Protein has a correlation of -0.68. The stronger correlation would be....
What is
Sugar versus Protein.
True or False: the residuals are squared and then added up to find the SSE, Sum of Squared Errors.
What is
True
The linear model for a local store's Number of Sales people working versus Sales is as follows:
Sales = 8,106 + 91.34n (where n=# of Sales People Working)
With 14 people working, the expected sales would be...
What is
$9,384.76
To use your calculator to find the residuals of a data set, you would...
What is
run linear regression test first.
Then immediately, go to Stat, Edit, go into the title bar of L3, up in the title bar, Stat, RESID
Suppose you have your data in L1 and L2 and you have set up your Stat Plot to graph the scatter plot.
To graph the linear regression equation on calculator you would....
What is
type the regression equation into y1 (in y=), then hit graph
A student says, "There was a very strong correlation of 1.22 between Sugar and Fat content." Explain the mistake made here.
What is
the value of the correlation coefficient r must be between -1 and +1.
The linear model for a local store's Number of Sales people working versus Sales is as follows: Sales = 8,106 + 91.34n (where n=Number of Sales People Working). If two people are working, the observed value is $8600. The residual would be...
What is
$311.32
An analysis of Math SAT versus Verbal SAT scores gives an equation of -
Predicted Verbal SAT Score = 171.333 + 0.6943m (where m=Math SAT Score).
If someone got a 520 on their Math section, their predicted verbal score would be...
What is
532.369
Find the t test statistic (t-value) and the p-value for a linear regression/correlation problem with a correlation coefficient of r=.72 and a sample size of n=50.
What is
t=7.188
p-value=3.79X10-9
or p-value<0.01
The linear model for a local store's Number of Sales people working versus Sales is as follows:
Sales = 8,106 + 91.34n (where n=# of Sales People Working)
The meaning of the y-intercept here would be...
What is
when no one is working, there would be $8106 in sales. This does not make sense, there should be no sales. This is just a starting point for the data.
Two variables produce a negative correlation.
Regarding the slope, this tells you....
What is
the slope will be negative or the line goes downward from left to right.