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A researcher wanted to determine whether eating PopTarts for breakfast increase the aggression of second graders during their morning play period. After feeding a group of 20 students PopTarts for breakfast she observed that, on average, the students committed 4.5 aggressive behaviors during their morning play period. In this example, the sample is:
A.) the 4.5 aggressive behaviors.
B.) the 20 students the researcher observed.
C.) all second graders.
D.) all second graders who ate PopTarts for breakfast.
the 20 students the researcher observed.

A researcher wanted to determine whether eating PopTarts for breakfast increased the aggression of second graders during their morning play period. After feeding a group of 20 students PopTarts for breakfast she observed that, on average, the students committed 4.5 aggressive behaviors during their morning play period. In this example, the descriptive statistic is:
A) the 4.5 aggressive behaviors.
B) the 20 students the researcher observed.
C) all second graders.
D) all second graders who ate PopTarts for breakfast.
the 4.5 aggressive behaviors.

A variable for which there is an infinite number of values between any two points on the scale is a ________ variable.
A) discrete
B) ratio
C) continuous
D) confounding
continuous

A person's grade point average on a scale from 0 to 4.0 would be a(n) ________ variable.
A) nominal
B) ordinal
C) interval
D) ratio
ratio

The amount of food a person eats each week (as measured in ounces) would be a ________ variable.
A) continuous and ratio
B) continuous and interval
C) discrete and interval
D) continuous and ordinal
continuous and ratio

Which of the following types of variables are considered scale variables by statistical computing packages such as SPSS?
A) continuous and ratio
B) continuous and interval
C) discrete and interval
D) ratio and interval
ratio and interval

Jonathon has taken the GRE three times. Every time he takes it he gets a 500 on the math section. This implies that:
A) the GRE is a valid test.
B) the GRE is a reliable test.
C) the GRE is neither a valid nor a reliable test.
D) Jonathon is not motivated to improve his score on the math section.
the GRE is a reliable test.

When a test measures what it is intended to measure, the test is said to be:
A) a scale variable.
B) continuous.
C) reliable.
D) valid.
valid.

In an experiment designed to assess the effects of disclosure of ingredients on the experience of taste, Lee, Frederick, and Ariely (2006) approached patrons at a local pub and asked them to taste and rate a new beer: the MIT Brew. Some participants were told about the secret ingredient in the beer (a few drops of balsamic vinegar) either before tasting (before condition) or after tasting but before rating (after condition). Other participants were not told anything regarding the secret ingredient (not told condition). Which of the following aspects of this study is an operational definition?
A) sample of patrons at the local pub
B) disclosure of the ingredients
C) experience of taste
D) participants' responses on the taste rating scale
participants' responses on the taste rating scale

Random assignment refers to a situation in which:
A) participants selfselect into a particular condition in the study.
B) the experimenter randomly determines whether to use a singleblind or doubleblind research design.
C) every person in the population has an equal chance of being selected for participation in the study.
D) every participant in the study has an equal chance of being assigned to any condition or level of the independent variable.
every participant in the study has an equal chance of being assigned to any condition or level of the independent variable.

A teacher calculated her students' test scores and found that overall they did very well. She found that out of the 23 students in the class, 19 of them got a 95 on her test. What percentage of students got a 95?
A) 82.61
B) 90.00
C) 88.00
D) 95.00
82.61

Bar graphs typically provide scores for ________ data.
A) nominal
B) ordinal
C) interval
D) continuous
nominal

A frequency polygon is similar to a histogram except that:
A) a frequency polygon can be drawn for a greater range of data values.
B) the polygon is typically used for ordinal rather than interval data.
C) lines are used to connect the midpoint of each interval.
D) in the polygon, frequencies appear on the xaxis.
lines are used to connect the midpoint of each interval.

Positively skewed distributions often result from:
A) a ceiling effect.
B) a floor effect.
C) unimodal curves.
D) symmetrical distribution.
a floor effect.

In a ________, the tail of the distribution extends to the left.
A) negatively skewed distribution
B) positively skewed distribution
C) ceiling effect
D) floor effect
negatively skewed distribution

A positive skew may have a tail that indicates extreme scores ________ the center of the distribution.
A) around
B) below
C) above
D) on either side of
above

17. (Figure: Reaching for Objects) The type of graph depicted in this figure is a:
A) bar graph.
B) Pareto chart.
C) histogram.
D) line graph.
18. (Figure: Reaching for Objects) What are the independent variables in this study?
A) visible object and hidden object
B) type of object and whether the object was visible or hidden
C) proportion of trials on which infants reached and type of object
D) novel object and familiar object
17) Bar graph, 18)type of object and whether the object was visible or hidden

What is the difference between a bar graph and a Pareto chart?
A) A Pareto chart is a bar graph with the bars ordered from highest (on the left) to lowest (on the right).
B) A Pareto chart is a line graph with bars depicted in three dimensions.
C) A Pareto chart is bar graph in which all the bars are stacked on top of one another.
D) There is no difference between a line graph and a Pareto chart.
A Pareto chart is a bar graph with the bars ordered from highest (on the left) to lowest (on the right).

Numbers that describe populations are called:
A) statistics.
B) parameters.
C) averages.
D) variables.
parameters.

Sixteen college freshmen were asked to record the number of alcoholic drinks that they typically consume in a week. Here are their data: 2, 4, 6, 0, 1, 10, 9, 0, 6, 3, 6, 8, 5, 4, 6, 2. What is the median number of alcoholic drinks consumed per week?
A) 4
B) 4.5
C) 5
D) 5.5
4.5

A bimodal distribution has ________ mode(s).
A) two
B) two or more
C) more than two
D) one
two

As part of their work in a research methods class, a group of psychology students devised a survey to assess the relation between stress and health. Each member of the class administered the survey to 10 friends, and the data were then pooled. What method of sampling was used?
A) random sampling
B) convenience sampling
C) representative sampling
D) population sampling
convenience sampling

Random assignment differs from random selection because:
A) random assignment deals with how participants for a study are chosen to begin with whereas random selection deals with how participants in a sample are assigned to levels of the independent variable.
B) random assignment deals with how participants in a sample are assigned to levels of the independent variable whereas random selection deals with how participants for a study are chosen to begin with.
C) random assignment is rarely achieved, but random selection is almost always achieved.
D) random assignment must be performed by the experimenter who is carrying out the study, but random selection can be carried out at the analysis stage.
random assignment deals with how participants in a sample are assigned to levels of the independent variable whereas random selection deals with how participants for a study are chosen to begin with.

Janice tosses a penny 10 times and finds that 7 of the 10 times the penny comes up heads and 3 of the 10 times the penny comes up tails. What should Janice conclude?
A) The penny is an unfair penny.
B) The expected relative frequency probability of getting heads when tossing a penny is 7/10.
C) It is more probable to get tails than it is to get heads when tossing a penny.
D) In the long term the expected relative frequency would be 5/10, but because she has tossed the penny only 10 times a different pattern has emerged.
In the long term the expected relative frequency would be 5/10, but because she has tossed the penny only 10 times a different pattern has emerged.

In a study of the effects of humor on memory, Schmidt (1994) had participants read either humorous sentences or nonhumorous sentences and then later tested participants' memory for the sentences. The experimental group in this experiment was:
A) the group of participants assigned nonhumorous sentences.
B) the group of participants assigned humorous sentences.
C) a third group of participants who were not asked to read any sentences.
D) There was no control group in this experiment.
the group of participants assigned humorous sentences.

A statement that there is no difference between populations is a:
A) negative statement.
B) null hypothesis.
C) research hypothesis.
D) positive statement.
null hypothesis.

On April 16, 2007, BBC news reported the results of a study done by Dr. David Lewis of the Mind Lab in the United Kingdom. Dr. Lewis found that eating dark chocolate had longer lasting excitatory effects on the body than did kissing a romantic partner. From his statement, it is evident that Dr. Lewis:
A) rejected the null hypothesis.
B) proved the research hypothesis.
C) failed to reject the null hypothesis.
D) accepted the research hypothesis.
rejected the null hypothesis.

If a researcher fails to reject the null hypothesis when the null hypothesis is in fact false, she has:
A) made a Type II error.
B) made a Type I error.
C) committed the gambler's fallacy.
D) fallen prey to the confirmation bias.
made a Type II error.

A fellow student failed to replicate the bystander effect, a wellestablished effect in social psychology. Because this student failed to find a statistically significant difference in helping behaviors as the number of bystanders increased, it is possible that the student:
A) made a Type II error.
B) made a Type I error.
C) committed a false positive.
D) committed the confounding variable error.
made a Type II error.

A Type I error is to a ________ as a Type II error is to a ________.
A) true positive; true negative
B) false positive; false negative
C) false negative; false positive
D) true negative; false positive
false positive; false negative

If a researcher rejects the null hypothesis when the null hypothesis is in fact true, she has:
A) made a Type II error.
B) made a Type I error.
C) committed the gambler's fallacy.
D) fallen prey to the confirmation bias.
made a Type I error.

If a distribution of scores has a mean of 50 and a standard deviation of 5, then a score of 40 has a z score that is ________ standard deviation(s) ________ the mean.
A) two; below
B) one; above
C) one; below
D) two; above
two; below

The mean for the population is 80 with a standard deviation of 5. Given a z score of 1.45, what is the raw score?
A) 88.00
B) 90.00
C) 87.25
D) 1.00
87.25

In a normal standard curve, approximately ________% of scores fall within 2 standard deviation from the mean
A) 34
B) 48
C) 96
D) 68
48

In a normal standard curve, which percentile corresponds to a z score of –1.0?
A) 16
B) 68
C) 96
D) 45
16

The symbol for the standard error is:

The formula for z based on the mean of a sample is:
A) z = (M – µM)/µS
B) z = (X – µM)/µS
C) z = (X – µM)/M
D) z = (M – µM)/M
z = (M – µM)/M

A z score is a measure of:
A) how far away from the mean a score is in terms of standard deviations.
B) how far away from the mean a score is in terms of inches.
C) strength of relationship between two variables.
D) strength of relationship between a score and its mean.
how far away from the mean a score is in terms of standard deviations.

If we wished to compare two scores that are measured on different scales, we would need to transform the scores into:
A) standard deviations.
B) means.
C) z scores.
D) population parameters.
z scores.

The mean of the distribution of a set of z scores is:
A) always 0.
B) always 1.
C) the same as the mean of the distribution of raw scores.
D) the score corresponding to the 50th percentile in the raw score distribution.
always 0.

A person with a z score of zero would have a raw score equal to:
A) the lowest score in the distribution of raw scores.
B) the mean of the distribution of raw scores.
C) the highest score in the distribution of raw scores.
D) zero.
the mean of the distribution of raw scores.

According to the 2003–2004 annual report of the Association of Medical and Graduate Departments of Biochemistry, the average stipend for a postdoctoral trainee in biochemistry was $31,331 with a standard deviation of $3,942. What would be the z score of a trainee making $42,566?
A) –2.85
B) –2.63
C) 2.85
D) 3.00
2.85

Jenna scored 40 on a standardized test of reading ability where the mean score is 50 and the standard deviation 10. Based on this information, what is Jenna's z score?
A) –2.0
B) 2.0
C) 1.0
D) –1.0
–1.0

If a distribution of scores has a mean of 55 and a standard deviation of 5, then a score of 70 has a z score that is ________ standard deviation(s) from the mean.
A) one
B) two
C) three
D) four
three

There are six sides on a die. What is the probability that in one roll, you will roll a 6
A) 17%
B) .17
C) .83
D) 83%
.17

A distribution made up of the means of many samples (rather than individual scores) approximates a normal curve, even if the underlying population is not normally distributed. This is referred to as
A) A Type 1 Error
B) The Law of Large Numbers
C) The Law of Means
D) The Central Limit Theorem
The Central Limit Theorem

Because the distribution of means is narrower than the distribution of scores, it has a _______ standard deviation, and this standard deviation is called the _______.
A) larger; population standard deviation
B) larger; standard error
C) smaller; population standard deviation
D) smaller; standard error
smaller; standard error

The GSS is a survey of approximately 2000 adults conducted each year since 1972, for a total of more than 38,000 people. During several years of the GSS, participants were asked how many close friends they have. The mean for this variable is 7.44 friends, with a standard deviation of 10.98. Imagine you randomly selected a sample of 100 people, and find that their mean number of close friends is 8.11. Calculate the standard error.
A) 1.098
B) 2.345
C) 1.297
D) 4.625
1.098

The outcome variable that we expect to change with changes in the independent variable is the ________ variable.
A) confounding
B) noise
C) dependent
D) extraneous
dependent

The variable that is manipulated or observed in order to determine its effects on another variable is the ________ variable.
A) scale
B) independent
C) dependent
D) confounding
independent

Withingroup designs are also called ________ designs.
A) repeatedmeasures
B) longitudinal
C) correlational
D) random assignment
repeatedmeasures

A researcher is interested in the effectiveness of natural remedies for allergies. The researcher randomly assigns to 30 allergy sufferers a treatment of herbal tea, homeopathic doses of the allergens, or a traditional antihistamine. What type of research design has the researcher employed?
A) withingroups
B) experimental
C) correlational
D) betweengroups
withingroups

An operational definition is one that:
A) can be flexibly implemented by any researcher.
B) defines a variable in terms of observable and measurable behaviors.
C) defines a variable in terms of a hypothetical construct.
D) is used to determine the independent variable of an experiment.
defines a variable in terms of observable and measurable behaviors.

A negative skew may have a tail that indicates extreme scores ________ the center of the distribution
A) around
B) below
C) above
D) on either side of
below

A graph that depicts the relation between two interval variables is a:
A) frequency table.
B) bar graph.
C) time series plot.
D) scatterplot.
scatterplot.

57. The symbol for the population standard deviation is:

z scores are useful because they:
A) allow us to convert raw scores to mean scores, compare scores from different samples, and transform populations into samples.
B) transform linear scores into nonlinear scores, convert nonlinear scores back into linear scores, and allow us to obtain comparisons between nonlinear and linear scores.
C) give us an understanding of where a score falls in relation to the mean of its underlying population, allow comparisons to be made between scores from different distributions, and permit the transformation of z scores into percentiles.
D) reduce the probability of Type I and Type II errors, allow us to compare raw scores with standard scores, and permit the transformation of raw scores into percentiles.
reduce the probability of Type I and Type II errors, allow us to compare raw scores with standard scores, and permit the transformation of raw scores into percentiles.

Given the properties of the standard normal curve, we know that ________% of all scores fall below the mean and _______% fall above the mean.
A) 68; 68
B) 50; 50
C) 34; 34
D) 48; 48
50;50

What type of statistics are the mean and standard deviation?
A) descriptive
B) inferential
C) hypothesis testing
D) experimental
descriptive

A researcher's decision regarding whether to reject the null hypothesis is based on:
A) the researcher's a priori theory regarding expected group differences.
B) independent confirmation by researchers in other laboratories.
C) the probability that group differences would be observed if there was no effect of the independent variable.
D) whether the results of the study have been replicated at least once.
the probability that group differences would be observed if there was no effect of the independent variable.

For a data set that has been skewed due to outliers, what measure of central tendency is most accurate and should be reported?
A) mean
B) median
C) mode
D) variance
median

What measure of variability is the square root of the average of the squared deviations from the mean?
A) variance
B) standard deviation
C) range
D) central tendency
standard deviation

The standard deviation (SD) is most commonly used to get a sense of how far the typical score of a distribution differs from the mean. In computing the SD, why is it necessary to square the deviations from the mean for each score?
A) The deviations are too small to have a variance without being squared.
B) There is no variability in the deviations of the scores prior to squaring.
C) Squaring numbers is fun.
D) The mean of the deviations balances out to zero due to negative and positive values.
The mean of the deviations balances out to zero due to negative and positive values.

The ________ is a distribution composed of many means.
A) standard normal curve
B) central limit theorem
C) standard error
D) distribution of means
distribution of means

The formula (X – µ)/ is used to calculate a:
A) raw score.
B) standard deviation.
C) z score.
D) mean distribution.
z score.

The formula z() + µ is used to convert a ________ to a ________.
A) raw score; z score
B) z score; raw score
C) raw score; standard error
D) z score; standard error
z score; raw score

z scores allow us to compare scores from:
A) different distributions.
B) linear distributions.
C) nonlinear distributions.
D) standard errors.
different distributions.

Random ________ is a process that ensures that every participant has an equal chance of being in any one of the experimental conditions and is common in scientific research, whereas random ________ is when every member of the population has an equal chance of being a participant and is much less common in experimental studies.
A) sampling; assignment
B) sampling; error
C) assignment; block design
D) assignment; sampling
assignment; sampling

In a famous experiment on the unreliability of eyewitness testimony, participants first watched a video of a car wreck and were then asked either “How fast was the car going when it hit the other car?” or “How fast was the car going when it smashed into the other car?” The hypothesis was that the word “smashed” would induce higher estimates of speed than the word “hit.” What would be the null hypothesis?
A) The “hit” group would estimate a lower speed than the “smashed” group.
B) Only the “smashed” group would estimate a high speed.
C) Both groups would give similar estimates of speed.
D) Neither group would estimate the speed at all.
Both groups would give similar estimates of speed.

A recent study on reorientation produced dramatic results when researchers found that college students ignore obvious landmarks while reorienting in a small confined space and performing a verbal task at the same time. However, several other studies, using the same methods at different universities, have not been able to replicate this finding. Is this important?
A) No; the exact same location and sample were not used.
B) No; replication is a form of plagiarism.
C) Yes; replication is the only way to ensure random sampling.
D) Yes; it demonstrates that these results are not generalizable.
Yes; it demonstrates that these results are not generalizable.

The GSS is a survey of approximately 2000 adults conducted each year since 1972, for a total of more than 38,000 people. During several years of the GSS, participants were asked how many close friends they have. The mean for this variable is 7.44 friends, with a standard deviation of 10.98. Imagine you randomly selected a sample of 100 people, and find that their mean number of close friends is 8.11. Calculate the z statistic for this sample.
A) 0.43
B) 1.27
C) 2.50
D) 0.61
0.61

Calculate the standard deviation of the following scores: 2, 3, 4, 5, 6, 7
A) 2.45
B) 1.71
C) 2.06
D) 1.29
1.71

If the standard deviation is 10, what is the variance?
A) 10
B) 5
C) 3.16
D) 100
100

If the variance is 9, what is the standard deviation?
A) 81
B) 18
C) 9
D) 3
3

If points on a scatterplot tend to form a line from lower left to upper right, the correlation is
A) positive
B) negative
C) nonexistent
D) 0
positive

A researcher wanted to determine whether eating PopTarts for breakfast increase the aggression of second graders during their morning play period. After feeding a group of 20 students PopTarts for breakfast she observed that, on average, the students committed 4.5 aggressive behaviors during their morning play period. In this example, the population is:
A) the 4.5 aggressive behaviors.
B) the 20 students the researcher observed.
C) all second graders.
D) PopTarts
all second graders.

A study that utilizes repeated measures on the same participants is called a
A) Betweengroups design
B) Survey
C) Withingroup design (or withinsubjects design)
D) Post facto design
Withingroup design (or withinsubjects design)

