QUIZ 2

What is the chart called when the paired data (the dependent and independent variables) are plotted?

Scatter Diagram

Assume the last squares is Y' = 10+20X. What does the value of 10 in the equation indicate

Y intercept

If all the plots on a scatter diagram lie on a straight line, what is the standard error of estimate?

0

Which value of R indicates a stronger correlation than 0.40?

0.50

A hypothesis test is conducted at the .05 level of significance to test whether or not the population correlation is zero. If the sample consists of 25 observations and the correlation coefficient is 0.60, then what is the computed value of the test statistic?

3.60

Suppose the least squares regression equation is Y' = 1.202 + 1.133x When x =3, what does Y' equal?

4.607

If r=1.00, what inferences can be made

All of the above are correct

Which of the following are true assumptions underlying linear regression: 1) for each value of X, there is a group of Y values which is normally distributed; 2) the means of these normal distributions of Y values all lie on the straight line of regression; and/or 3) the standard deviations of these normal distributions are equal?

All of them

What does the coefficient of correlation of 0.70 infer?

Coefficient of determination is 0.49

If the coefficient of determination is 0.90, the coefficient of correlation is 0.81.

False

In the ANOVA table for regression, the total sum of squares in the sum of the treatment and error sum of squares.

False

If the correlation between two variables is close to one, the association is

Strong.

A coefficient of correlation, r close to 0 (say, 0.08) shows that the relationship between two variables is quite weak.

True

A scatter diagram is a chart that portrays the relationship between two variables.

True

A t test is used to test the significance of the coefficient of correlation.

True

In regression analysis, the predicted value of Y' rarely agrees exactly with the actual Y value. i.e., we expect some prediction error.

True

One General assumption underlying linear regression is that the Y values are statistically dependent of the X values. ( When answering this question consider the point of regression in the first place. That is... what are we trying to detect with regard to the X and Y values?)

True

One assumption underlying linear regression is that for each value of X there is a group of Y values that is normally distributed.

True

Originated by Karl Pearson about 1900, the coefficient of correlation describes the strength of the relationship between two, interval or ratio-scaled variables.

True

The standard error of estimate measures the accuracy of our prediction.

True