Exam 3: Finding Relationships Among Variables

Statisticians often refer to the pivot tables as contingency tables or crosstabs.

Joint categories for categorical variables cannot be used to make inferences about the relationship between the individual categorical variables.

A scatterplot allows one to see:

A trend line on a scatterplot is a line or a curve that fits the scatter as well as possible

If the sample is a good representation of the population,what percentage of those who spent the weekend studying should we expect to do poorly on the final exam?

The cutoff for defining a large correlation is >0.7 or <-0.7.

The most common data format is

A perfect straight line sloping downward would produce a correlation coefficient equal to

Correlation and covariance measure

What is the average annual salary of the employed Internet users in this sample?

If Cov(X,Y)= - 16.0,variance of X = 25,variance of Y = 16 then the sample coefficient of correlation r is

The correlation between two variables is a unitless and is always between -1 and +1.

The limitation of covariance as a descriptive measure of association is that it

The Excel function that allows you to count using more than one criterion is

What percentage of these Internet users who are married.

We do not even try to interpret correlations numerically except possibly to check whether they are positive or negative

If the standard deviations of X and Y are 15.5 and 10.8,respectively,and the covariance of X and Y is 128.8,then the coefficient of correlation r is approximately 0.77.

Approximate the percentage of these Internet users who are currently employed.

If we draw a straight line through the points in a scatterplot and most of the points fall close to the line,there is a strong positive linear relationship between the two variables.

Which of the variables have a negative linear relationship with the household's average monthly expenditure on utilities?