Linear Equation
Calculator Skillz
Y-intercept + Other Random Things
Correlation
Interpretation
100
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. What does the slope of 103.929 mean in this context?
For every 1 mb increase in capacity, the price increases by $103.929.
100
List the steps to find the linear regression of a line given a data set in your calculator.
1) Enter the table using the "+"
2) Once all data is entered click the scatterplot line that looks like a racing flag on the sidebar of the table
100
In slope intercept form, y=mx+b, this variable represents the y-intercept.
What is b?
100
Describe a correlation of -0.9 in terms of strength (weak, moderate, or strong) and direction.
Very strong, negative (slope of line is negative so line is going downward from left to right).
100
We summarized the relationship between x = height of a student (in inches) and y = number of steps required to walk the length of a school hallway, with the regression line y^=113.6−0.921x.
For this model, technology gives r = -0.632. Interpret this value.
There is a moderately strong, negative, linear correlation between a students height and the number of steps required to walk the length of a school hallway. As height increases, the number of steps required decreases.
200
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, what would you expect the price to be?
$226.475
200
What variable is used to represent the correlation coefficient?
r
200
What does r = -0.75 tell us about a linear regression?
It has a fairly strong, negative correlation (the slope is negative so the line is going downward from left to right)
200
Sketch a data set with a correlation correlation of 0.98.
200
We summarized the relationship between x = height of a student (in inches) and y = number of steps required to walk the length of a school hallway, with the regression line y^=113.6−0.921x
Interpret the slope.
For every additional inch in height, the predicted number of steps to walk the length of the hallway will decrease by 0.921 steps.
300
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). What does the slope mean in this situation?
For every increase of 1 sales person working, sales increase by $91.34.
300
What command do you use to get the standard deviation for univariate data?
stdevp(List name)
300
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)
What is the y-intercept?
$8,106
300
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. Which has a stronger correlation?
Sugar versus Protein.
300
We summarized the relationship between x = height of a student (in inches) and y = number of steps required to walk the length of a school hallway, with the regression line y^=113.6−0.921x
Interpret the y-intercept. Is this meaningful in context?
If a student is 0 inches tall, it will take them 113.6 steps to walk the length of the hallway. This is not meaningful because a student wouldn't be 0 inches tall.
400
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, what would you expect sales to be?
$9,384.76
400
You need the IQR for a univariate set of data. What command do you use to find the five number summary that contains the quartile values you need to calculate the IQR?
Enter the data into a list and then use the stats(listname) feature to get the five number summary. Then subtract Q3 and Q1 to get the IQR.
400
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)
What are the expected sales when there are 100 people working?
$17,240
400
A student says, "There was a very strong correlation of 1.22 between Sugar and Fat content." Explain the mistake made here.
Correlation must be between -1 and +1.
400
We summarized the relationship between x=shoe size and y=height.
For the model, technology gives r = .03. Interpret this value.
There is no relationship
500
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).
What would you predict someone's verbal score to be if they got a 520 on their Math section?
532.369
500
What is the format for entering a list of data?
Give the list a variable and type the variable, then the equals sign, the square bracket, and then enter the data set.
i.e. for list L type L=[1, 2,3,4]
500
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)
What is the meaning of the y intercept, does it make sense?
The intercept means there would be $8,106 in sales when no one is working. This doesn't make sense for a brick and mortar store because there should be no sales when no one is working but there could be online sales if they have that capability.
500
Two variables produce a negative correlation. How will this affect the slope?
The slope will be negative.
500
We summarized the relationship between x = height of a student (in inches) and y = number of steps required to walk the length of a school hallway, with the regression line y^=113.6−0.921x
For this model, technology gives r = 0.63. Interpret this value.
About 39.9% of the variability in number of steps required to walk the length of a school hallway is accounted for by the least-squares regression line with x = height (in)