Chapter 15/16 item bank

what is not needed to compute the y-intercept using the method of least squares?

Mxy

what is not needed to compute the slope using the method of least squares?

SSy

in a sample of 22 people, suppose we conduct an analysis of regression with one predictor variable. if Fobt= 4.07, then what is the decision for this test at .05 los? (F critical= 4.35)

X does not significantly predict Y

the more that the variability in... is associated with regression variation, the more likely it is that X predicts Y

Y

both sources of variation in an analysis of regression measure the variability in...

Y only

t/f the coefficient of determination is the square root of the correlation coefficient

false

the most common measure of effect size for the correlation coefficient is called....

the coefficient of determination

an unanticipated variable not accounted for in a research study that could be causing or associated with observed changes in one ore measured variables is called...

a confound variable

a statistical procedure used to describe the strength and direction of the linear relationship between two factors is called.....

a correlation

the scores or data points for a regression analysis are typically reported in....

a scatter plot

which of the following is a limitation for interpreting a correlation?

correlations do not demonstrate cause and effect; outliers can change the direction and/or strength of the correlation; conclusions should not be drawn beyond the range of scores measured

using an analysis of regression, the variability in Y that is predicted by X is measured by the .....

regression variation

using an analysis of regression, the variability in Y that is associated with error is measure by the...

residual varaition

what is the computation for the standard error of estimate?

the square root of the mean square residual

to summarize correlations, we report....

the strength of the correlation, the direction of the correlation, the p value; critical values do not need to be reported

the coefficient of determination is....

a measure of effect size, mathematically equivalent to eta-squared, equal to the correlation coefficient squared

correlation coefficient ranges from -1 to +1, with values closer to +1 indicating.....

a stronger relationship between two factors

the standard error of estimate is used as a measure of .... in predictions using the equation of a regression line

accuracy

which of the following is used to determine the significance of predictions made by a best fitting linear equation?

analysis of regression

the method of least squares is used to determine the.... straight line to a set of data points

best-fitting

the coefficient of determination (r^2) is mathematically equivalent to.....

eta-squared

t/f a correlation of r=.50 in a sample of 15 participants is statistically significant for a two tailed test at .05 los

false

t/f a positive correlation is always stronger than a negative correlation

false

t/f if r=.25, then the coefficient of determination is .06

false

t/f in an analysis of regression there are three sources of variation: regression, residual, and error

false

t/f the coefficient of determination is a measure of significance

false

t/f the larger the standard error of estimate, the more accurately known values of X will predict values of Y

false

t/f the null hypothesis for a test of the relative contribution of two predictor variables is that adding one factor improves the prediction of variance in Y beyond that already predicted by the second factor

false

t/f the regression line is not always the best fitting line to a set of data points

false

the assumption that there is equal variance or scatter of data points dispersed along the regression line is referred to as....

homoscedasticity

which of the following is the assumption that the best way to describe the pattern of data is using a straight line?

linearity

which of the following is used to determine the linear equation that "best fits" a set of data points?

method of least squares

a correlation coefficient can .... demonstrate cause

never

the correlation coefficient is used to measure____ and _____ of the linear relationship between two factors

strength;direction

t/f the value of the sum of products can be positive or negative

true

t/f the sign of a correlation coefficient indicated the direction of the relationship between two factors

true

linear regression describes the extent to which... predicts.....

x;y, the predictor value; the criterion value, the known variable; the to-be-predicited variable

to summarize any type of regression analysis using APA format, what do we report? and what do we not report?

you report test statistic, degrees of freedom, and the p value; you don't report the critical values

t/f three assumptions for a correlation are homoscedasticity, linearity, and normality

true

the denominator of the correlation coefficient measures the extent to which two variables....

vary independently

correlation coefficient ranges between .... and ....

-1 and +1

t/f the numerator of the formula for the slope of a regression line is equal to the sum of products

true

t/f linear regression is used to measure the extent to which a criterion variable causes changes in a predictor variable

false

t/f restriction of range occurs when an unanticipated variable not accounted for in a research study that could be causing or associated with observed changes in one or more measured variables

false

t/f the assumption of normality requires that range of scores observed is a sample is the same of the possible range of scores in the population

false

t/f the predictor variable is a known value that is issued to predict the value of another variable

true

t/f the left over or remaining variation attributed to error in an analysis of regression is called residual variation

true

t/f correlation does not show causation

true

t/f for a simple linear regression with one predictor variable, we report the test statistic, degrees of freedoms and p value for the regression analysis

true

t/f homoscendasticity is the assumption that there is an equal variance of data points dispersed along the regression line

true

t/f linearity is the assumption that the best way to describe a pattern of data is using a straight line

true

t/f outliers can change both the direction and strength of a correlation coefficient

true

t/f the closer the data points fall to the regression line, the more closely two factors are related

true

t/f the correlation of r=.38 in a sample of 30 participants is statistically significant for a two tailed test at .05 lost

true

a researcher computes a perfect negative correlation, in which each data point falls exactly on the regression line. in this example, the value of the standard error of estimate will be...

equal to 0

t/f the correlation coefficient varies between 0 and 1 and can never be negative

false

t/f the data points for pairs of scores are often summarized in a bar chart

false

t/f the degrees of freedom residual is equal to the number of criterion variables

false

t/f the denominator of the Pearson correlation coefficient measures the extent to which two factors vary together

false

t/f we can evaluate the significance of the relative contribution of each factor by first determining the differences between group means

false

t/f we do not need to know the value of the slope to compute the value of the y-intercept

false

what are the steps to evaluate the significance for the relative contribution of each factor?

find r^2 for the other predictor values; complete the F table and make a decision; identify SS accounted for by the predictor variable of interest

which of the following is the assumption that there is an equal variance of data points dispersed along the regression line?

homoscedasticity

the regression equation measures....

how far each data point deviates from the line that most closely fits the data

the degrees of freedom associated with residual variation are equal to....

n-2

a researcher measure the extent to which years of marriage predict perceptions of forgiveness. which factor is the criterion variable?

perceptions of forgiveness

the normal assumption states that the population of x and y scores for a bivariate normal distribution, such that....

population of x and y scores are normally distributed; for each x score the distribution of y scores is normally distributed; for each y score, the distribution of x scores is normally distributed

outliers change the..... of a correlation

sign (-,+)

a researcher measures the extent to which the speed at which people eat predicts calorie intake. which factor is the predictor variable?

speed at which people eat

an estimate of the standard deviation or distance that data points fall from the regression line is measured by the...

standard error of estimate

which of the following statements is true regarding the sources of variation present in an analysis of regression?

the closer the data points fall to the regression line, the more the variance in Y will be attributed to regression variation

select the description below that identifies the following correlation: r=.28, p<.01

the correlation is positive, it is statistically significant, and the coefficient of determination is .08

the degrees of freedom associated with regression variation are equal to....

the number or predictor variables

t/f the coefficient of determination is mathematically equivalent to eta-squared

true

t/f the equation for a straight line is y=bX+a

true

t/f the slope is a measure of the change in y relative to the change of x

true

t/f the standard error of estimate provides an estimate of the standard distance that data points fall from the regression line

true

t/f to compute the standard error of estimate, we take the square root of the mean square residual

true

t/f we can evaluate the relative contribution of each predictor variable by evaluating the significance of the added contribution of each factor

true

t/f when most of the variability in Y is attributed to the regression variation, it is more likely that X predicts Y

true

the numerator of the correlation coefficient measures the extent to which two variables....

vary together and covary

if f=2.04 for the relative contribution of one factor, then what is this value when converted to a t statistic?

1.43; f= root F