Exam 2 Review

A least squares regression line _____. a.may be used to predict a value of y if the corresponding x value is given b.implies a cause-effect relationship between x and y c.can only be determined if a good linear relationship exists between x and y d.is only used for positively correlated data

a. may be used to predict a value of y if the corresponding x value is given

The symbol σ is used to represent the _____. a.standard deviation of a population b.variance of a population c.standard deviation of a sample d.variance of a sample

a. standard deviation of a population

The descriptive measure NOT measured in the same units as the original data is the _____. a.variance b.standard deviation c.median d.mode

a. variance

If the data distribution is symmetric, the skewness is _____. a.0 b..5 c.1 d.-.5

a. 0

In regression analysis, the variable that is being predicted is the _____. a.dependent variable b.independent variable c.intervening variable d.controlled variable

a. dependent variable

The descriptive measure of dispersion that is based on the concept of a deviation about the mean is the _____. a.standard deviation b.interquartile range c.weighted mean d.range

a. standard deviation

In a simple regression analysis (where y is a dependent and x an independent variable), if the slope is positive, then it must be true that _____. a.there is a positive correlation between x and y b.there is a negative correlation between x and y c.the y-intercept is 0 d.there is no correlation between x and y

a. there is a positive correlation between x and y

Which of the following symbols represents the mean of a population? a.μ b.σ^2 c. d.σ

a. μ

The correlation coefficient ranges from which two values? a.−1 and +1 b.0 and 1 c.1 and 100 d.minus infinity and plus infinity

a. −1 and +1

A regression analysis between sales (in $1000s) and price (in dollars) resulted in the following equation: ​ = 50,000 − 8x ​ The above equation implies that an increase of _____. a.$8 in price is associated with an increase of $8,000 in sales b.$1 in price is associated with a decrease of $8,000 in sales c.$1 in price is associated with a decrease of $42,000 in sales d.$1 in price is associated with a decrease of $8 in sales

b. $1 in price is associated with a decrease of $8,000 in sales

In simple linear regression, r2 is the _____. a. correlation coefficient b. coefficient of determination c. sum of the squared residuals d. estimated regression equation

b. coefficient of determination

In a regression analysis, the variable that is used to predict the dependent variable _____. a.usually is denoted by y b.is the independent variable c.is the dependent variable d.must have the same units as the variable doing the predicting

b. is the independent variable

It is possible for the coefficient of determination to be _____. a.larger than 1 b.less than 1 c.less than 0 d.between -1 and 1

b. less than 1

Generally, which of the following is the least appropriate measure of central tendency for a data set that contains outliers? a.median b.mean c.mode d.midrange

b. mean

After the data have been arranged from smallest value to largest value, the value in the middle is called the _____. a.range b.median c.mean d.interquartile range

b. median

An important measure of location for categorical data is the _____. a.range b.mode c.median d.mean

b. mode

For data skewed to the left, the skewness is _____. a.less than 1 b.negative c.positive d.between 0 and .5

b. negative

A data point (observation) that does not fit the trend shown by the remaining data is called a(n) _____. a.residual b.outlier c.point estimate d.y-intercept

b. outlier

A(n) _____ is an unusually small or unusually large data value. a.z-score b.outlier c.median d.sample statistic

b. outlier

The equation that describes how the dependent variable (y) is related to the independent variable (x) is called _____. a.the correlation model b.the regression model c.correlation analysis d.the least squares criterion

b. the regression model

A mean computed in such a way that each data value is given a weight reflecting its importance is referred to as a(n) _____. a.heavy mean b.weighted mean c.trimmed mean d.important mean

b. weighted mean

A numerical measure of linear association between two variables is the _____. a.variance b.z-score c.correlation coefficient d.standard deviation

c. correlation coefficient

When dividing a data set into four parts, the division points are referred to as the _____. a.midpoints b.class lower limits c.quartiles d.percentiles

c. quartiles

The standardized residual is provided by dividing each residual by its _____. a.mean residual b.z-score c.standard deviation d.corresponding x value

c. standard deviation

Which of the following symbols represents the mean of a sample? a.σ b.σ ^2 c.μ d.

d.

Which of the following values of r indicates the strongest correlation? a.0 b..361 c..82 d.-.9

d. -.9

The empirical rule states that, for data having a bell-shaped distribution, the portion of data values being within one standard deviation of the mean is approximately _____. a.50% b.33% c.95% d.68%

d. 68%

If the variance of a data set is correctly computed with the formula using n − 1 in the denominator, which of the following is true? a.The data set could be either a sample or a population. b.The data set is a population. c.The data set is from a census. d.The data set is a sample.

d. The data set is a sample.

If a data set has an even number of observations, the median _____. a.is the observation recorded most often b.cannot be determined c.must be equal to the mean d.is the average value of the two middle items when all items are arranged in ascending order

d. is the average value of the two middle items when all items are arranged in ascending order

A numerical measure, such as a mean, computed from a population is known as a _____. a.sample parameter b.sample statistic c.population statistic d.population parameter

d. population parameter

The difference between the largest and smallest data values is the _____. a.coefficient of variation b.interquartile range c.variance d.range

d. range

A procedure used for finding the equation of a straight line that provides the best approximation for the relationship between the independent and dependent variables is _____. a.the mean squares method b.the most squares method c.correlation analysis d.the least squares method

d. the least squares method

If there is a very strong negative correlation between two variables, then the correlation coefficient must be _____. a.very close to 1 b.very close to -0.5 c.exactly 0 d.very close to -1

d. very close to -1

Which of the following symbols represents the size of a sample? a.N b.σ ^2 c.σ d.n

d. n

The median of the data set is _____. a.always very close in value to the mean b.larger than the mean c.smaller than the mean d.preferred over the mean when the data set contains outliers

d. preferred over the mean when the data set contains outliers

When the data are positively skewed, the mean will usually be _____. a.greater than the mode b.greater than the median c.less than the mode d.less than the median

greater than the median

The numerical value of the coefficient of determination _____. a.is positive if the correlation coefficient is negative b.is always larger than the correlation coefficient c.is negative if the correlation coefficient is negative d.is always smaller than the correlation coefficient

is positive if the correlation coefficient is negative

If the correlation coefficient is a positive value, then the slope of the regression line _____. a.must also be positive b.is dependent on the value of the y-intercept c.can be 0 d.must be negative

must also be positive

Regression analysis is a statistical procedure for developing a mathematical equation that describes how _____. a.one independent and one or more dependent variables are related b.several independent and several dependent variables are related c.one dependent and one or more independent variables are related d.two independent variables are related

one dependent and one or more independent variables are related

If two variables, x and y, have a strong linear relationship, then _____. a.there may or may not be any causal relationship between x and y b.x causes y to happen c.y causes x to happen d.the slope of the regression equation must be negative

there may or may not be any causal relationship between x and y

In regression analysis, the independent variable is typically plotted on the _____. a.y-axis of a scatter diagram b.x-axis of a scatter diagram c.y-axis of a histogram d.x-axis of a histogram

x-axis of a scatter diagram

Larger values of r2 imply that the observations are more closely grouped about the _____. a.least squares line b.average value of the dependent variable c.origin d.average value of the independent variables

a. least squares line

A regression analysis between sales (y in $1000) and advertising (x in dollars) resulted in the following equation: = 50,000 + 6x ​ The above equation implies that an increase of _____. a.$1 in advertising is associated with an increase of $6,000 in sales b.$6 in advertising is associated with an increase of $6,000 in sales c.$1 in advertising is associated with an increase of $56,000 in sales d.$1 in advertising is associated with an increase of $6 in sales

a. $1 in advertising is associated with an increase of $6,000 in sales

The proportion of the variation in the dependent variable y that is explained by the estimated regression equation is measured by the _____. a.coefficient of determination b.confidence interval estimate c.correlation coefficient d.standard error of the estimate

a. coefficient of determination

A measure of the strength of the relationship between two variables is the _____. a.correlation coefficient b.standard error of the estimate c.confidence interval estimate d.slope b1 of the estimated regression line

a. correlation coefficient