Statistics

If we compute a correlation on data that come only from the middle of the X distribution (restricted range) rather than from the entire range, the correlation is likely to be ______ the correlation from the entire range

Smaller than

Type of correlation used to find out whether theres a relationship between one interval variable and one ordinal variable?

Spearman

Type of correlation used with any ranks or ordinal scales:

Spearman

coefficient of determination is equal to...

r squared

To know whether theres a relationship btwn two variables, you draw a line around the outer edges of a scatterplot. You can tell there is no relationship when

the scatterplot is either circular or elliptical, with the ellipse being parallel to the X axis

When no relationship btwn two variables, the value of every Y' is equal to

the value of the Y-intercept

In a correlational analysis, N stands for the

total number of pairs of scores

The sum of the deviations of the true Y scores from the predicted Y' scores is always

zero

A regression line is usually used when

the correlation coefficient is not 0.0

Master's degree-Candice-rainfall and height of ground water- which formula?

(E XY)-(E X)(E Y) ------------- square root of N......

Which of the following r-values indicates the weakest relationship between two variables?

+0.03

Calculate the appropriate correlation coefficient for the following data where 0 = not depressed and 1 = depressed (reading speed test score (X) and number of books read (Y))

+0.59

Calculate the appropriate correlation for data of runner, runner on race preparedness survey, and rank of race finish

+0.83

Calculate the appropriate correlation coefficient for the following data (Participant, Reading speed test score [X], number of books read [Y])

+0.95

Which of the following r-values indicates the strongest relationship between two variables?

-0.89

Calculating for the appropriate correlation coefficient of Employee, number of units produced, and minutes spent in break room

-0.92

Calculate the appropriate correlation for the following (employee, visits to break room, number of units produced)

-0.97

Y' = -0.85X + 20.93

...

Y' = 1.64X - 3.08

...

When r = 0.0, the slope of the regression line equals...

0

When r = 1.0, then Sy equals

0

The Y-intercept is the value of Y' when X =

0.0

if no relationship btwn two variables, the slope of the regression line will equal

0.0

Student test grocery memorability with images and without images- What is probability of obtaining a sample mean of 10 or higher?

0.0062 (lowest answer)

Which of the following is the criterion that psychologists usuall use to determine the likelihood that a sample mean was obtained by chance?

0.05=p

If probability of getting z score btwn the mean and +1 stand. deviation is 0.3413, what is probability of getting a z score lower than -1 standard deviation?

0.1587 (lowest answer)

Burnout and therapists relationship

0.28

president of college to survey students; probability for freshmen?

0.33

What is probability of getting a sample mean btwn 500 and 520 if pop mean is 500 and stand. dev. of sampling distribution is 20?

0.3413

Your profess. told the class that 20% of the class receives ...As...Bs..Cs...Ds..Fs. What is the probility that the student sitting next to you will recieve an A or F?

0.35

Advertising executive wanted to know about ad campaign against children smoking...; what is probability of obtaining a sample mean of -0.70 or lower (more negative)?

0.3632

Stress level + test score proportion of variance accounted for is

0.58

If probability of getting z score btwn the mean and +1 stand. deviation is 0.3413, what is probability of getting a z score of +1 or less?

0.8413 (highest answer)

12.43

12.43

A point on the scatter plot represents how many values?

2 (X and Y)

What is the slope of the regression equation: Y' = 0.56X + 2.41?

2.41

What is the slope of the regression equation: Y' = 2.69X - 3.92?

2.69

A "weak" relationship between two variables is represented by

A large spread of Y scores at each X score

How would a statistician define probability?

A mathematical statement indicating the likelihood of an event when we randomly sample a particular population

What kind of relationship is represented by a line slanting downward from left to right?

A negative relationship

"the bigger they are, the harder they fall" describes...

A positive linear correlation

Why can we never be sure that a sample represents a population?

A random sample may poorly represent the population , or it may represent a population that is different

The "error" in a SINGLE prediction is equal to the degree to which a participant's _____ score deviates from the _______.

Actual; corresponding predicted score

When the correlation coefficient representing the relationship between X and Y is intermediate, then all of the following are true except...

All data points fall on the regression line

when rolling a pair of dice, probability of rolling a total point value of (7) is 0.17, if you rolled a pair of dice 1,000 times and the point value of 7 appears 723 times, what would you conclude?

Although not impossible, this outcome is so unlikely that the fairness of these dice is questionable

Negative correlation

As one variable increases, the other decreases

Positive correlation

As one variable increases, the other variable increases

Prof. Miller found correlation btwn a "need for affiliation" and # of hours spent watching television is -.69; he should conclude...

As we observe people with higher and higher need for affiliation, we see a tendency for those people to spend less and less time watching television

One assumption of linear regression is...

At each X, the sample of Y scores should represent an approximately normal distribution

What statistic should be used to find out whether there is a relationship between hours spent participating in sports and GPA?

The Pearson correlation coefficient

Study at state University; negative correlation btwn smoking and lung capacity; after passing appropriate inferential test, what do the researchers do next?

Calculate the linear regression equation

In a non-linear or curvilinear relationship, as the X scores change, the Y scores...

Change consistently, but in more than one direction

If there is a relationship between "amount of coffee consumed" and "nervousness", then as the amount of coffee consumed increases, the amount of nervousness...

Changes in some consistent, predictable manner

What is the basis of all inferential statistics?

Deciding whether or not a sample of scores is representative of a particular population

If you see the notation E XY what should you do?

First multiply each X by its partner Y, then sum the results

If you see the notation (E X)(E Y) what should you do?

First sum the Xs, then sum the Ys, then multiply the sums

The mean of the population is 200, vaience = 100, probability of 5% only in upper tail...

Since the z value does not fall iwhtin the region of rejection, we should not conclude this sample mean represents some other population

A study about college aptitude of seniors... z score of +1.89, critical value for region of rejection is +1.96, what is correct conclusion?

Since the z value does not fall within the region of rejection, we should not conclude this sample mean represents some other population

In general, a positive correlation means that as the values of one variable ______, there is a tendency for the values of the other variable to _______.

Increase; increase

Words comprehended in a sentence; sample mean z = 3.00, critical values of +1.96, what should psych conclude?

It is an unlikely sample for the population of looking times ofr other words and probably represents some other population

Which of the following is NOT true of linear regression equation?

It is the equation from which the correlation coefficient is calculated

What does a correlation coefficient do?

It quantifies the pattern in a relationship

A nonlinear correlation looks like what?

Low to high and back to low, like a rainbow!

Formula for slope of the regression line?

N (E XY) -(E X)(E Y) __________________ N(E X^2)-(E X^2)

what type of relationship does a horizontal line parallel to the X axis represent?

No relationship

Sample mean with z score of -2.00, critical value is +1.96, what is correct conclusion?

Since the z value falls within the region of rejection, we should conclude this sample mean likely represents some other population

Phsyic. Fitness of 65 and older men with sit-ups;

Since z scores falls within the region of rejection, we should conclude this sample mean likely represents some other population

What statistic should be used to find out whether there is a relationship between years of education and annual income?

The Pearson correlation coefficient

The strength of a relationship is indicated by the extent to which ________ paired with each individual value of the _________ variable.

One value of the Y variable is; X

Type of correlation used when both variables are interval or ratio:

Pearson

Professor Johnston and strong correlation between neckties and strokes; claims wearing neckties causes strokes. What error has he made?

Professor Johnston is drawing a causal conclusion from correlational findings

When we square the correlation coefficient to produce r(squared), the result is equal to the

Proportion of variance accounted for

what do we call that portion of the sampling distribution in which values are considered too unlikely to have occurred by chance?

Region of rejection

The best-fitting line through a scatterplot is known as the __________ line.

Regression!

If the correlation coefficient turns out to be a relatively high value, then the value of Sy will be

Relatively low

When knowledge of a relationship is used, the average error remaining after predictions have been made based on the relationship is

S^2y

Which of the following is not true of the criterion?

Samples that meet the criterion occur more than 5% of the time

__________ occurs when random chance produces a sample statistic that is not equal to the population parameter it represents

Sampling error

The weakest relationship of Study A, Study B, and Study C is...

Study B

When r = 0.0, the value of Sy is equal to

Sy

Which correlation coefficient should we use if we want to find out whether a relationship exists between two vairables that represent pairs of ordinal scores?

The Spearman rank-order correlation coefficient

Linear regression is defined as the procedure for determining

The best-fitting straight line in a linear relationship

"the self-confidence of a group of students is positively correlated with their chances of getting through the course"- what does this statement mean?

The chances of passing the course tend to increase as the self-confidence scores of the students increase

What is the critical value?

The inner edge of the region of rejection

When a sample mean is different from the mean of the sampling distribution, two alternatives must be considered; the sample mean may represent _______, or it may represent _______.

The population poorly; a different population

Relationship between linear and scatter plot diagrams?

The regression line is the best-fitting line through a scatter plot

Mean = 100, stand. error of samp. diet. = 10, mean = 80,

The sample mean does not occur very often by chance in the sampling distribution of means and probably did not come from the given population

What can we conclude when the absolute value of a z-score for a sample mean is larger than the critical value?

The sample mean does not represent the particular raw score population on which the sampling distribution is based

Mean = 100, stand. error of samp. diet. = 10, mean = 110

The sample mean occurs very often by chance in the sampling distribution of means and probably did not come from the given population

What can you conclude about a sample mean that falls within the region of rejection?

The sample probably represents some population other than the one on which the sampling distribution was based

The criterion determines

The size of the region of rejection

In the regression equation, the slope summarizes __________ and the Y-intercept indicates_________.

The steepness and direction of the regression line; the value of Y' when X = 0

Professor Helgin has found that the correlation btwn length of an index finder and the person's IQ is -0.09. He should conclude that...

There is a very weak relationship between the length of the index finger and IQ because r is nearly 0

which relationship is stronger, r = +0.62 or r = -0.62?

There is no difference in the strength of the two relationships

which of the following is correct regarding means that fall within the region of rejection when the critical values are +1.96?

They occur with a probability of 5%

What can we conclude about a sample mean that is found to lie in the region of rejection? It is extremely ____ to have occured by chance, and represents ____

Unlikely; some other population

Statisticians use linear regression to

predict unknown Y scores from known X scores

Which of the following formulas represents the Y intercept of the regression line?

Y(bar) - (b)(Xbar)

Study about relationship btwn women's age and attitude about marriage using Pearson, what mistake was made?

You only surveyed young women in college causing a restriction of range

When we divide the error remaining after we use the relationship to predict Y scores by the total error when we use the mean to predict the Y scores and then subtract 1 from the result, the final result is

proportion of variance accounted for

"The more you save, the less you spend" describes...

a negative linear correlation

Which of the following best describes knowing the relative frequency of every possible event in a population?

a probability distribution

which of the following accurately decribes a theoretical probability distribution? It is based on...

a theoretical model of the relative frequency of events in a population

Using correlation design, a researcher found a relationship between the healthiness of one's heart and the amount of fish oil in one's diet. The researcher should conclude that...

although a relationship exists, one cannot infer that changes in one variable are causing changes in another variable

If we decide to reject the idea that a sample represents a particular population, bc the sample mean lies within the region of rejection,

although probability is low, our decision may be wrong

If we decide not to reject the idea...

although the probability is low, our decision may be wrong...

In general, a zero correlation means that...

as the values of one variable increase, there is no tendency for the values of the other variable to change in any consistent, predictable fashion

The standard error of the estimate is defined as the

average spread of actual Y scores around the predicted Y' scores

The "error" in all predictions made from a sample using linear regression is the...

avergage spread of actual Y scores around the predicted Y' scores

If we calculate a correlation coefficient and we find that there is a relationship between the two variables, we...

cannot conclude that changes in one variable cause changes in the other variable

How can we determine the representativeness of a sample mean for a particular population?

convert the sample mean to a z score and compare the z score to the critical value

At a basic level, when deciding whether a sample is representative of a particular population, we

decide against low-probability events in favor of high-probability events

When heteroscedasticity exists, the problem with r is that it..

does not accurately describe the strength of the relationship for all Xs

To predict a Y' score from a given X score using the regression constants, we would

first multiply X by the slope and then add the Y-intercept

compared to a strong relationship, a weak relationship btwn two variables results in

greater prediction error and a larger value of Sy

In a linear relationship, as the X scores increase, the Y scores change...

in only one direction

You roll a die twice, and both times you roll a 6. What type of events are these two rolls?

independent

As a general rule, when statisticians determine the probability of events, they assume that the events are __________ and sampled __________.

independent; with replacement

26 red cards and 26 black cards...

is the same as it has always been if the deck is a fair deck

Linear regression is important because

it is used to predict unknown Y scores based on X scores from a correlated variable

The scores that lie in the tails of a normal distribution have a ____ frequency and a ____ probability of occurring

low; low

The purpose of probability and inferential statistics is to...

make decisions about the population that have a good chance of being correct

When a z score is not in the region of rejection, we should

not reject the idea that the sample represents the raw score population

We calculate the proportion of variance accounted for because it is the statistical basis for evaluation

of the usefulness of a relationship

Regression line is best fitting because

on average, the regression line passes through the center of the various Y scores

The best-fitting line through a scatterplot is known as the

regression line

In an experimental design _________, whereas in a correlational design ________.

researchers assign each person an X score and then measure the score on the Y variable; researchers measure scores on variables that a participant has already experienced

Suppose you take candy out of jar, look at color, & put it back in jar before randomly selecting next piece. This sampling is called...

sampling with replacement

when plotting correlational data, the appropriate graph to use is the

scatterplot!

We should do a scatterplot of the data when we compute a correlation because the scatterplot allows us to

see the nature of the relationship between the two variables

Water quality study; pop = 100, ox= 25, area of 0.05,

since the z value falls within the region of rejection, we should conlucde this sample mean likely represents some other population

the slope of a line is a number indicating the

slant of the line and the direction in which it slants

In looking at the regression constants, we know the relationship is negative if the

slope value is negative

standard error of the estimate formula

square root of 1-r ^2

Which correlation coefficient should we use if we want to find out whether a relationship exists between two variables that are both interval or ratio variables?

the Pearson correlation coefficient

Homoscedasticity occurs when

the Y scores at all Xs are spread out to the same degree

Heteroscedasticity occurs when

the Y scores have a different degree of spread at different Xs

which of the following accurately describes an empirical probability distribution? It is based on...

the computed relative frequency of observed events

In general, the greater the proportion of variance accounted for,

the more accurately we can predict behavior

a probability distribution gives us...

the probability of every possible event in a population

Two events are said to be independent when...

the probability of one event is not influenced by the occurrence of the other event

An event's relative frequency in the population equals...

the probability of the event

How is the relative frequency of an event defined?

the proportion of times an event occurs in the population of events

the coefficient of alienation is interpreted as

the proportion of vairance not accounted for

the coefficient of determination is interpreted as the proportion of variance accounted for

the proportion of variance accounted for

when +1.645 is used as the critical value instead of +1.96,

the region of rejection is all placed in the positive tail