STAT 1430: Final

True or False: If Ha is not equals, you have to double the probability of being beyond your test statistic to get your p-value.

True

True or False: The p-value will change if you get a new data set

True

True or False: A researcher is trying to use January temperatures to predict latitude. This means January temperature is the X (independent) variable and latitude is the Y (dependent) variable.

True X predicts Y

Suppose the correlation between X =price of a gallon of gasoline and Y = price of a gallon of milk is r = .30 Should we go on and try to make predictions for milk prices using gasoline prices using a straight line?

No weak correlation

True or False: Correlation is affected by outliers

True

If a residual is negative, then that data point lies _________________ the regression line.

below

Suppose the equation y = 3.45 - 2.58x represents a valid regression equation and X can be used to predict Y. From this information, we know that X and Y have _____________ correlation.

negative

True or False: Suppose the correlation between yards rushing and yards passing is .6. That means the correlation between feet rushing and feet passing is .6 x 12 (since you multiply yards by 12 to convert to feet).

False correlation is unit-free

SSE

Sum of Squares for Error

Suppose you have 4 data sets whose scatterplots all show possible linear relationships. The four data sets have correlations of -0.10, +0.25, -0.90, and +0.80, respectively. Which of the correlations shows the strongest linear relationship?

-0.90

The personnel department keeps records on all employees in a company. Here is the information they keep in one of their data files: Employee identification number Last name First name Middle initial Department Number of years with the company Salary ($) Education Level (high school, some college, or college degree) Age (years) Which of the following combinations of variables would be appropriate to examine with a scatterplot? Age and Salary. Salary and Education Level. All of these choices are correct. Education Level and Age.

Age and Salary correlation uses quantitative variables only

Your boss gives you the following regression equation: Selling price = $5,240 + $33.80 (Number of Square Feet). How do you interpret the slope for this equation?

As square feet increases by 1, the selling price increases by $33.80

Suppose: 1. all the points on a scatterplot lie perfectly on a straight line going uphill 2. the mean of X and the mean of Y are both 2 3 the standard deviations of X and Y are exactly the same. Can you find the equation of the best fitting line with this information? (Hint: Think of the '5 number' way of finding the best-fitting line.)

Yes (mean of x, mean of y, correlation, SD of x, SD of y)

True or False: Suppose the correlation between two variables X and Y is .8. That means the correlation between Y and X is -.8.

False

True or False: The value of α will change if you get a new data set

False

True or False: No or weak correlation means there is no relationship at all

False correlation indicates linear relationship, but there may be a different type of relationship