PSYCHOLOGY EXAM 1

The correlation coefficient ranges between ____ and ____.

-1, +1

Which of the following is true for normal distributions?

-Around 70% of the scores will be located within one standard deviation of the mean.

Which of the following sets of scores has the least variability? 20, 22, 25, 30, 31 1, 2, 3, 10, 11, 12 16, 17, 18, 19, 20 5, 7, 8, 9, 12, 13

16, 17, 18, 19, 20

A sample consists of n = 16 scores. How many of the scores are used to calculate the range?

2

For the linear equation Y = 2X + 4, if X increases by 1 point, by how much will Y increase? Group of answer choices

2 points

A researcher selects a sample of 6 males and 11 females. She asks participants to rate the likelihood they would do female-stereotyped jobs (such as nursing or school teaching) on a scale from 1 = not likely at all to 5 = very likely. Men indicated that they would be less likely to do these jobs (M = 2.1) compared with women (M = 4.3). What is the weighted mean for this entire sample of 17 participants? Group of answer choices

3.5

It is only appropriate and possible to calculate the variance and standard deviation as measures of variability for variables measured using a(n) _____ scale of measurement.

Both interval and ratio

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FALSE

The standard error of estimate provides a measure of standard distance between the predicted Y values from a regression equation and the actual Y values from the data.

TRUE

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a. notebook computer use and final grade b. -.140 c. small

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

vary together and covary

For a regression equation with a positive slope, if an X value is above the mean for the X scores, then the predicted Y value will be above the mean for the Y scores. Group of answer choices

true

One or two extreme data points can have a dramatic effect on a computed Pearson's r value for a correlation.

true

Why do deviation scores have to be squared before calculating the standard deviation?

If deviation scores are not squared, then the average distance from the mean will always equal 0.

A distribution of scores is positively skewed. Which is the most probable order, from smallest to largest, for the three measures of central tendency?

Mode, median, mean

For a negatively skewed distribution, the mode is usually larger than either the median or the mean

TRUE

For the regression equation, Ŷ = -2X + 6, if the X value is above the mean (positive deviation), what can be determined about the predicted Y value? Group of answer choices

The predicted Y value will be below the mean for the Y scores.

Which of the following statements is consistent with a research study conducted with the correlational method? Group of answer choices

Two variables are measured, and there is only one group of participants.

Three research methods common to research in the behavioral sciences are...

experimental, correlational, and quasi-experimental

If the population variance is 4, then the standard deviation will be 16.

false

Inferential statistics allow researchers to _____.

make predictions and generalizations about populations

The sample variance is computed by dividing SS by ______; whereas the population variance is computed by dividing SS by ______. Group of answer choices

n-1,n

Consider the mathematical expressions of Σ(X + 2) and Σ(X + 2)2. A valid generalization is that _____.

the first equation typically will yield a lower computed value

The mean can take on any value and the standard deviation can take on any positive value. Therefore,

there are an infinite number of possible normal distributions.

Which of the following is not an aspect involved in computing the sum of products (SP) of deviations?

-subtracting the total sum of squares collapsed across all scores

Which of the following is a possible value for the standard deviation of a normal distribution? Group of answer choices .5 −2 −∝ 0

.5

A negative correlation means that decreases in the X variable tend to be accompanied by decreases in the Y variable.

FALSE

Decide whether each of the following describes an experiment, quasi-experiment, or a correlational method. -A researcher tests whether the dosage level of a some drug (low, high) *causes* significant differences in health. -A researcher tests whether citizens of differing political affiliations (Republican, Democrat) will show differences in attitude toward morality. -A researcher measures the relationship between annual income and life satisfaction. -A researcher assesses how students perform on exams in relation to how much time they spend watching lecture videos.

a. experiment b. quasi-experiement c. correlational d. use all 3: correlational, quasi-experiment, experiment

Match the type of data with its description Nominal Ordinal Interval Ratio

a. number assigned to represent something or someone b. conveys order or rank only c. no true zero and distributed in equal parts d. True zero and distributed in equal parts

Sample variability by itself tends to underestimate population variability. To adjust for this, the sample variances are computed by dividing SS by n - 1, which produces a more unbiased estimate. Taking the average value of the these adjusted sample variances from all possible random samples will _____ the population variance. Group of answer choices

equal

The slope value found in regression tells us

how much variable Y changes for each unit of change in variable X

The advantage of squaring the deviation of each score from the mean and then summing is that:

it produces a minimal positive solution that is not zero, so long as all the scores are not exactly the same value

A sociologist records the annual household income (in thousands of dollars) among a sample of families living in a high-crime neighborhood. Locate the lower, median, and upper quartiles for the times listed below. Hint: First arrange the data in numerical order. (Enter numbers only). 32 29 51 37 40 46 37 19 31 41 Lower Quartile: --- thousand dollars Median:--- thousand dollars Upper Quartile: ---thousand dollars

lower:29.25 median: 39 upper: 47.25

For a perfectly symmetrical distribution, which relationship is always true?

mean = median = mode

Which of the following actions would have the effect of either changing the size or direction (sign) of a Pearson r value pertaining to a set of X and Y scores? Group of answer choices

multiplying each X and Y score by a negative constant value

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n=10

If a distribution of scores is shown in a bar graph, the scores were measured using a(n) _____ scale of measurement. Group of answer choices

nominal or ordinal

The mean can take on any value and the standard deviation can take on any positive value. Therefore,

there are an infinite number of possible normal distributions

A variable is a characteristic or condition that changes or has different values for different individuals.

true

A variable is a characteristic or condition that changes or has different values for different individuals. Group of answer choices

true

For a regression equation with a positive slope, if an X value is above the mean for the X scores, then the predicted Y value will be above the mean for the Y scores.

true

For linear regression, the value of SSresidual is used directly when calculating the standard error of the estimate.

true

The sample mean is unbiased because the average of all possible sample means derived for samples of a specific size is equal to the population mean.

true

The value obtained for the sum of products, SP, determines the sign (+/-) for the Pearson correlation value. Group of answer choices

true

Under what circumstances would a score that is below the mean by 3 points appear to be very far from the mean?

when the standard deviation is much less than 3

Which of the following is true for the quantity Σ(X - μ)? Group of answer choices

This is the sum of the deviations, and it is always 0.

Recording the type of people with whom other students choose to study describes ________ types of data; whereas recording the number of hours spent studying per week describes ________ types of data. Group of answer choices

qualitative, quantitative

A pianist records the number of hours she spent playing the piano during the past 10 weeks. She recorded the following: 2.2 3.0 3.3 5.3 5.8 6.1 6.7 6.8 7.2 9.3 The data the pianist collected is:

ratio

Which of the following is an example of a distribution with NO variability? Group of answer choices scores: 5, 5, 5, 5, 5, and 5 scores: 1, 2, 3, 4, 5, and 6 scores: 3, 5, 4, 4, 5, and 3 scores: 3, 3, 3, 3, 33, and 3

scores: 5, 5, 5, 5, 5, and 5

A sample with a variance of s2 = 36 has a standard deviation equal to s = 6.

true

A sample of n = 10 scores has a mean of M = 3. What is ΣX for this sample?

30

A population of N = 10 scores has a standard deviation of σ = 2. What is the value of SS, the sum of the squared deviations, for this population? Group of answer choices12

40

A set of n = 25 pairs of scores (X and Y values) in a research study has a Pearson correlation of r = 0.80. What percentage of the variance for the Y scores is predicted by its relationship with X? Group of answer choices

64%

A researcher increases the sample size, which will...

decrease the variance.

A discrete variable must be measured on a nominal or an ordinal scale. Group of answer choices

false

A researcher finds a significant positive correlation of r = 0.63 between the amount of time spent watching television and blood pressure for a sample of 40-year-old men. This means that watching more television causes higher blood pressure.

false

For a severely skewed distribution, the mean often provides a better measure of central tendency than the median or the mode.

false

Sample variability by itself tends to underestimate population variability. To adjust for this, the sample variances are computed by dividing SS by n - 1, which produces a more unbiased estimate. Taking the average value of the these adjusted sample variances from all possible random samples will _____ the population variance.

smaller than

A sample has a mean of M = 50. If one new person is added to this sample, what effect will this have on the sample mean?

the sample mean will decrease

It is possible for none of the actual (observed) data points to be located on the regression line derived from the regression equation. Group of answer choices

true

Which of the following is true? -Around 35% of the scores will be located within 1SD of the mean. -Around 95% of the scores will be located within 1SD of the mean. -Around 56% of the scores will be located within 1SD of the mean. -Around 68% of the scores will be located within 1SD of the mean.

-Around 68% of the scores will be located within 1SD of the mean.

Which of the following is a consequence of increasing variability?

-The distance from one score to another tends to increase, and a single score tends to provide a less accurate representation of the entire distribution.

Match the descriptions: Population Sample Values that describes a population are termed Values that describes a sample are termed

A. entire set of individuals B. representative subsets C. parameters D. Statistics

A Pearson correlation value (r) indicates the exact degree of accuracy in which a researcher can predict a participant's score on a second variable from their score on a first variable.

FALSE

A Pearson correlation value of r = -0.90 indicates that the data points are clustered far from a line that slopes down to the right. Group of answer choices

FALSE

A researcher finds a significant positive correlation of r = 0.63 between the amount of time spent watching television and blood pressure for a sample of 40-year-old men. This means that watching more television causes higher blood pressure. Group of answer choices

FALSE

For a population, a deviation score is computed as X - σ.

FALSE

If the population variance is 4, then the standard deviation will be 16. Group of answer choices

FALSE

To compute the summation of x2 you first add the scores, then square the total.

False

Why is the mode is the only appropriate measure of central tendency to use with data measured on a nominal scale?

In a nominal scale the categories are not numbers on which calculations can be performed.

Assuming that other factors are held constant, a correlation of r = -0.95 between variables in one research study will result in more accurate predictions than a correlation of r = +0.70 in another research study.

TRUE

It is possible for none of the actual (observed) data points to be located on the regression line derived from the regression equation.

TRUE

The sample mean is unbiased because the average of all possible sample means derived for samples of a specific size is equal to the population mean. Group of answer choices

TRUE

The value obtained for the sum of products, SP, determines the sign (+/-) for the Pearson correlation value.

TRUE

Which statement below is consistent conceptually with what a computed Pearson's r value represents?

The Pearson's r value represents the degree to which X and Y scores covary together relative to how much X and Y scores vary separately.

Which statement below is consistent conceptually with what a computed Pearson's r value represents? Group of answer choices

The Pearson's r value represents the degree to which X and Y scores covary together relative to how much X and Y scores vary separately.

From the regression equation Ŷ = -2X + 6, what can be determined about the correlation between X and Y?

The correlation will be negative.

A group of researchers measure the weight of five participants prior to a clinical weight loss intervention. They record the following weights (in pounds): 160, 310, 210, 110, and 260 pounds. The mean is 210 pounds.Using the original example of five weights, the researchers added a sixth participant to the sample. If the sixth participant weighed 210 pounds, will the mean increase, decrease, or not change? Group of answer choices

The mean will stay the same.

Which of the following is true for the quantity Σ(X - μ)?

This is the sum of the deviations, and it is always 0.

Which of the following is not an aspect involved in computing the sum of products (SP) of deviations? Group of answer choices

subtracting the total sum of squares collapsed across

A linear regression equation has b = 3 and a = -6. What is the predicted value of Y for X = 4?

Ŷ = 6