PSY 317

For a population with σ = 10, a score that is located 20 points above the mean would have a z-score of ____. +20 +2 -2 cannot answer without knowing the mean

+2

Which of the following deviation scores corresponds to the score that is farthest away from the mean? 0 5 -5 -10

-10

The mean for any distribution corresponds to a z-score of ____. 0 1 N cannot be determined from the information given

0

What is the variance for the following population of scores? Scores: 2, 2, 2, 2 0 2 4 16

0

Using the following table. X f 5 1 4 2 3 4 2 1 1 2 How many individuals had a score of X = 2? 1 2 3 4

1

The next three questions concern the following frequency distribution table. X f 5 1 4 2 3 4 2 1 1 2 For these data, n = ___. 10 15 29 cannot be determined from the table

10

For the following scores, what is (∑ X) 2? Scores: 0, 1, 6, 3 20 46 100 400

100

A population of N = 10 scores has a mean of μ = 24 with SS = 160, a variance of σ 2 = 16, and a standard deviation of σ = 4. For this population, ∑( X − μ) 2 has a value of ____. 0 4 16 160

160

A population of scores has μ = 80. In this population, a score of X = 86 corresponds to z = +3. What is the population standard deviation? 2 3 6 12

2

A sample of n = 5 scores produces SS = 20. The variance for this sample is ____. 20/5 = 4 20/4 = 5 the square root of 4 the square root of 5

20/4 = 5

A population of n = 5 scores produces SS = 20. The variance for this population is ____. 20/5 = 4 20/4 = 5 the square root of 4 the square root of 5

20/5 = 4

Using the following table. X f 5 1 4 2 3 4 2 1 1 2 For these data, ∑X is ___. 10 15 29 cannot be determined from the table

29

For the sample shown in the frequency distribution table, the median is ____. X f 5 1 4 5 3 4 2 1 1 1 3 3.5 4 15/2 = 7.5

3.5

One item on a questionnaire asks students how many times in a typical week they eat at a fast-food restaurant. The responses for a sample of n = 10 students are summarized in the frequency distribution. What is the median for this sample? X f 5 or more 2 4 3 3 2 2 1 1 1 0 1 4 3.5 31/10 = 3.1 The median cannot be determined for these data.

3.5

For the population of scores shown in the frequency distribution table, the mean is ____. X f 5 2 4 1 3 4 2 3 1 2 15/5 = 3 15/12 = 1.25 34/5 = 6.80 34/12 = 2.82

34/12 = 2.82

For the sample shown in the frequency distribution table, the mode is ____. X f 5 1 4 5 3 4 2 1 1 1 3 3.5 4 5

4

In a population with μ = 60, a score of X = 58 corresponds to a z-score of z = −0.50. What is the population standard deviation? 1 2 4 cannot be determined without additional information

4

A sample of n = 5 scores has SS = 40. If the same five scores were a population, then the value obtained for the population SS would be ____. 40 5(40/4) = 50 4(40/5) = 32 4(40) = 200

40

What is the median for the following set of scores?Scores: 1, 2, 5, 6, 17 3.5 5 5.5 6

5

A set of N = 20 exam scores has a mean of μ = 50. The instructor discovered that an error was made grading one exam, so 20 points are added to that student's score. After adding the 20 points, what is the new mean for the class? 50 51 70 cannot be determined from the information given

51

What is the mean for the following scores? Scores: 1, 4, 13 3 5 6 9

6

For a perfectly symmetrical distribution with μ = 30, the median would have a value ____. equal to 30 greater than 30 less than 30 cannot be determined from the information given

= to 30

One item on a questionnaire asks, "How many siblings (brothers and sisters) did you have when you were a child?" A researcher computes the mean, the median, and the mode for a set of n = 50 responses to this question. Which of the following statements accurately describes the measures of central tendency? Because the scores are all whole numbers, the mean will be a whole number. Because the scores are all whole numbers, the median will be a whole number. Because the scores are all whole numbers, the mode will be a whole number. All of the other options are correct descriptions.

Because the scores are all whole numbers, the mode will be a whole number.

What does it mean to say that the sample variance is an unbiased statistic? No sample will have a variance that is exactly equal to the population variance. Each sample will have a variance that is equal to the population variance. If many different samples are selected, the average of the sample variances will be equal to the population variance. If many different samples are selected, the sample variances will consistently underestimate the population variance.

If many different samples are selected, the average of the sample variances will be equal to the population variance.

In a sample of n = 6, five individuals all have scores of X = 10 and the sixth person has a score of X = 16. What is the mean for this sample? M = 13 M = 11 M = 13.2 not enough information to find the mean

M=11

A population with a mean of μ = 8 has ∑ X = 40. How many scores are in the population? N = 5 N = 320 N = 8/40 = 1/5 cannot be determined from the information given

N = 5

One item on a questionnaire asks students how many times in a typical week they eat at a fast-food restaurant. The responses for a sample of n = 10 students are summarized in the frequency distribution. What is the mean for this sample? X f 5 or more 2 4 3 3 2 2 1 1 1 0 1 M = 4 M = 3.5 M = 31/10 = 3.1 The mean cannot be determined for these data.

The mean cannot be determined for these data.

A sample has a mean of M = 72. If one person with a score of X = 58 is removed from the sample, what effect will it have on the sample mean? The sample mean will increase. The sample mean will decrease. The sample mean will remain the same. cannot be determined from the information given

The sample mean will increase.

Instead of showing the actual number of individuals in each category, a population frequency distribution graph usually shows ____. an estimated frequency a grouped frequence a relative frequency a hypothetical frequency

a relative frequency

The normal distribution is an example of _____________. a histogram showing data from a sample a polygon showing data from a sample a bar graph showing data from a population a smooth curve showing data from a population

a smooth curve showing data from a population

The value for the standard deviation is determined by ____. the extreme scores (both high and low) in the distribution the extremely high scores in the distribution the middle scores in the distribution all of the scores in the distribution

all of the scores in the distribution

What kind of frequency distribution graph shows the frequencies as bars that are separated by spaces? a bar graph a histogram a polygon All of the other choices are correct.

bar graph

In a study evaluating the effectiveness of a new medication designed to control high blood pressure, one sample of individuals is given the medicine and a second sample is given a placebo. Blood pressure is measured for each individual. For this study, what is the dependent variable? the medication the placebo blood pressure the individuals given the medication

blood pressure

A variable that has an infinite number of possible values between any two specific measurements is called a(n) ____ variable. independent dependent discrete continuous

continuous

Statistical techniques that summarize, organize, and simplify data are classified as ____. population statistics sample statistics descriptive statistics inferential statistics

descriptive statistics

A sample of n = 5 scores has SS = 20. The variance for this sample is 4.

false

Adding a new score to a distribution will always change the value of the mean.

false

For any population, a z-score of +1.00 corresponds to a location exactly 10 points above the mean. true false

false

In a frequency distribution graph, the frequency values are presented on the horizontal axis and the scores (or measurement categories) are presented on the vertical axis.

false

It is possible for a distribution to have more than one mean.

false

On a 100-point test, you have a score of X = 73. Based on this information, you know that you definitely scored above the median.

false

Statistical procedures that attempt to organize and summarize data are classified as inferential statistics.

false

There is enough information in a grouped frequency distribution table to obtain a complete listing of the original set of scores.

false

To find ∑Χ for the scores in a frequency distribution table, you simply add the values in the X column.

false

For the past 20 years, the high temperature on April 15th has averaged μ = 62 degrees with a standard deviation of σ = 4. Last year, the high temperature was 72 degrees. Based on this information, last year's temperature on April 15th was ____. a little above average far above average above average, but it is impossible to describe how much above average There is not enough information to compare last year with the average.

far above average

A z-score of z = +3.00 indicates a location that is ____. near the center of the distribution slightly above the mean far above the mean in the extreme right-hand tail of the distribution The location depends on the mean and standard deviation for the distribution.

far above the mean in the extreme right-hand tail of the distribution

One sample of n = 4 scores has a mean of M = 10, and a second sample of n = 8 scores has a mean of M = 20. If the two samples are combined, the mean for the combined sample will be ____. equal to 15 greater than 15 but less than 20 less than 15 but more than 10 None of the other choices is correct.

greater than 15 but less than 20

What type of frequency distribution graph is shown in the figure on the left side where the bars are touching? histogram polygon bar graph cumulative graph

histogram

Sample variance provides an unbiased estimate of the population variance. The term unbiased means ____. for any sample, the sample variance will equal the population variance for large samples, the sample variance will equal the population variance if sample variance is computed for many samples, the average sample variance will equal the population variance None of the other choices is correct.

if sample variance is computed for many samples, the average sample variance will equal the population variance

Statistical methods that use sample data to answer general questions about a population are called ____. parameters statistics descriptive statistics inferential statistics

inferential statistics

To determine the size of the difference between two measurements, a researcher must use a(n) ____ scale of measurement. nominal ordinal or interval interval or ratio ratio

interval or ratio

What is the best description for the shape of this distribution where the tail is off to the left? normal symmetrical positively skewed negatively skewed

negatively skewed

If a distribution of scores is shown in a bar graph, you know that the scores were measured on a ___ scale of measurement. nominal or ordinal ordinal or interval interval or ratio discrete or continuous

nominal or ordinal

Which of the following is an example of a discrete variable? height reaction time number of brothers and/or sisters age

number of brothers and/or sisters

After measuring two individuals, a researcher can say that Tom's score is greater than Bill's, but cannot specify how much greater. The measurements must come from a(n) ____ scale. nominal ordinal interval ratio

ordinal

A researcher is curious about the average IQ of registered voters in the state of Florida. If this average could be obtained, it would be an example of a ____. sample statistic population parameter

parameter

What type of frequency distribution graph is shown in the figure on the right side where the points are connected by a line histogram polygon bar graph cumulative graph

polygon

Although research questions usually concern a ____, the actual research is typically conducted with a ____. sample, statistic population, parameter sample, population population, sample

population, sample

What is the shape of the distribution for the following set of data? Scores: 1, 2, 2, 2, 2, 3, 3, 4, 5, 6 symmetrical positively skewed negatively skewed cumulative

positively skewed

What shape would you expect for the distribution of scores from a very hard exam for a large class of students? positively skewed negatively skewed symmetrical normal

positively skewed

After measuring a set of individuals, a researcher finds that Bob's score is three times greater than Jane's score. These measurements must come from a(n) ____ scale. nominal ordinal interval ratio

ratio

A researcher is interested in the effect of St. John's Wort on memory. A group of 25 college students are selected to participate in a research study. The average memory score obtained for the 25 students is a ____. sample statistic population parameter

statistic

What is the first step to be performed when computing ∑( X-2) 2? square each value subtract 2 points from each score sum the values computer 22 = 4

subtract 2 points from each score

What is the final step to be performed in the following mathematical expression? ∑( X + 2) 2 square each value sum the squared values add 2 points to each value square the sum of the values

sum the squared values

A researcher is measuring problem-solving times for a sample of n = 20 children. However, one of the children fails to solve the problem, so the researcher has an undetermined score. What is the best measure of central tendency for these data? the mean the median the mode Central tendency cannot be determined for these data.

the median

A sample of n = 4 scores has SS = 12. What is the standard deviation for the sample? 3 the square root of 3 4 the square root of 4

the square root of 4

The value for the range is determined by ____. the two extreme scores (highest and lowest) in the distribution the extremely high scores in the distribution the middle scores in the distribution all of the scores in the distribution

the two extreme scores (highest and lowest) in the distribution

A deviation of zero corresponds to a score exactly equal to the mean.

true

A population of N = 5 scores has SS = 20. The variance for this population is 4.

true

A professor records the height (in inches) for each student in a class. If these data are presented in a frequency distribution graph, it would be acceptable to use a polygon.

true

A researcher records how much time each participant needs to solve a series of problems. This is an example of a continuous variable.

true

A researcher records the gender of each child born in the county hospital during the month of June. This researcher is measuring a discrete variable.

true

After the scores in a sample have been organized into a frequency distribution table, you can determine the number of scores (n) by simply adding the values in the f column of the table.

true

For a specific set of scores, the value you obtain for SS will be the same whether the set of scores is a sample or a population.

true

For any population, a z-score of +1.00 corresponds to a location above the mean by one standard deviation.

true

For the following scores, (∑ X) 2 = 100. Scores: 1, 2, 3, 4

true

If a deviation score has a negative (−) sign, then the X value is below the mean.

true

If a distribution of scores is transformed into z-scores then the sum of the positive z-scores will be exactly equal to the sum of the negative z-scores.

true

If two individuals in a population have identical X scores, they also will have identical z-scores.

true

It is possible to have a distribution of scores where no individual has a score exactly equal to the mean.

true

Measuring the number of students in each psychology course would be an example of a discrete variable.

true

No single method will provide a good measure of central tendency for every possible set of data.

true

On an exam with μ = 70, you have a score of X = 76. You should expect a better grade if σ = 3 than if σ = 12.

true

One purpose for central tendency is to describe an entire distribution by identifying the most representative score.

true

The normal-shaped distribution is an example of a symmetrical distribution.

true

To determine how much difference there is between two individuals, you must use either an interval or a ratio scale of measurement.

true

Transforming an entire distribution of scores into z-scores will not change the shape of the distribution.

true

When calculating SS, it is impossible to obtain a value less than zero unless a mistake is made.

true

Under what circumstances would a score that is located 5 points above the mean be considered relatively close to the mean? when the population mean is much less than 5 when the population mean is much greater than 5 when the population standard deviation is much less than 5 when the population standard deviation is much greater than 5

when the population standard deviation is much greater than 5

Under what circumstances would a score that is 15 points above the mean be considered an extreme score? when the population mean is much larger than 15 when the population standard deviation is much larger than 15 when the population mean is much smaller than 15 when the population standard deviation is much smaller than 15

when the population standard deviation is much smaller than 15

For a distribution of scores, which of the following z-score values represents the location closest to the mean? z = +0.50 z = +1.00 z = -1.00 z = -2.00

z = +0.50

For a distribution of scores, which of the following z-score values represents the most extreme location on the left-hand side of the distribution? z = +1.00 z = +2.00 z = -1.00 z = -2.00

z = -2.00

A population of scores has μ = 20 and σ = 5. If two points are added to every score in the population, then the new values for the mean and standard deviation would be ____. μ = 20 and σ = 5 μ = 22 and σ = 5 μ = 20 and σ = 7 μ = 22 and σ = 7

μ = 22 and σ = 5

A population of scores has μ = 20 and σ = 5. If every score in the population is multiplied by 2, then the new values for the mean and standard deviation would be ____. μ = 20 and σ = 5 μ = 40 and σ = 5 μ = 20 and σ = 10 μ = 40 and σ = 10

μ = 40 and σ = 10

In a population with σ = 8, a score of X = 42 corresponds to a z-score of z = −0.50. What is the population mean? μ = 34 μ = 38 μ = 46 μ = 48

μ = 46

Suppose you earned a score of X = 54 on an exam. Which set of parameters would give you the highest grade? μ = 50 and σ = 2 μ = 50 and σ = 8 μ = 52 and σ = 2 μ = 52 and σ = 8

μ = 50 and σ = 2

If you have a score of X = 75 on an exam, which set of parameters would give you the highest position within the class? μ = 70 and σ = 5 μ = 70 and σ = 10 μ = 60 and σ = 5 μ = 60 and σ = 10

μ = 60 and σ = 5

A population with μ = 85 and σ = 12 is transformed into z-scores. After the transformation, the population of z-scores will have a standard deviation of ____. σ = 12 σ = 1.00 σ = 0 cannot be determined from the information given

σ = 1.00

On an exam with a mean of μ = 70, you have a score of X = 65. Which of the following values for the standard deviation would give you the highest position within the class? σ = 1 σ = 5 σ = 10 cannot determine from the information given

σ = 10

How would the following mathematical operation be expressed in summation notation? "Add two points to each score, square the resulting value, then find the sum of the squared numbers." ∑ X + 2 ^2 (∑ X + 2) ^2 ∑( X + 2) ^2 ∑ X^ 2 + 2

∑( X + 2) 2^