PSY 200 Block 1

A New York Times article published on April 24, 2007, reported the research of Dr. Giorgio Vallortigara, a neuroscientist at the University of Trieste, Italy, and his two colleagues. The researchers asked whether a dog wags its tail in a preferred direction in response to positive stimuli and in another direction in response to negative stimuli. To answer their question, they recruited 30 dogs that were family pets. Filming each dog from above, they allowed it to view (through a slat in its cage) three positive stimuli separately, in order of descending positivity: its owner, an unfamiliar human, and a cat. All the dogs responded by wagging their tails to the right. But when the dogs were presented with an unfamiliar, aggressive dog, a negative stimulus, all dogs wagged their tails to the left. Which of the following is the null hypothesis for this study?

A dog's tail wagging will be the same in response to positive stimuli as to negative stimuli.

Frances conducted an informal survey among the women living in her sorority house. One of the questions asked, "How many drinks do you have per week?" Frances found that the results for this question were negatively skewed. What does this mean?

Most women in the house drink a lot, but a few don't drink at all.

Suppose you conduct a study examining the effect of an after-school enrichment program on children. You believe that students enrolled in the program will show increased intelligence (IQ) scores. Which of the following statements might represent the research hypothesis for this study?

The average IQ score for children in the enrichment program is higher than for children not in the program.

In comparing frequency tables with grouped frequency tables for the same set of data, which of the following would be true?

If the data set is large, the grouped frequency table would be easier to decipher.

Which of the following is NOT an assumption of the z test?

The distribution of the sample is normal.

How can the normal curve help in catching cheaters?

It helps by identifying events that are unlikely to have occurred by chance.

What is the advantage of using the interquartile range as a measure of variability as compared to the range?

It is less affected by outliers because the most extreme values are not used in the calculation.

An analysis, by Gerber and Malhotra (2006), of articles published in two political science journals indicated that researchers may be cheating by "playing" with their data. What evidence was used to support this idea?

More research results were found with z scores slightly greater than 1.96 and fewer results slightly less than 1.96 than would be expected by chance.

Which of the following is true regarding histograms?

The frequency of each interval is represented by the height of the bars.

Imagine that scores on a recent exam were distributed as follows: 32, 70, 72, 75, 78, 79, 81, 84, 100. Which of the following statements is true regarding the interquartile range of this distribution?

The interquartile range will be unaffected by the extreme scores.

The first step in calculating the median is to:

arrange the scores in ascending order.

Replication means that a researcher:

attempts to reproduce the original findings of a study.

The extent to which research findings from one sample or context can be applied to other samples or contexts is called:

generalizability

Experiments are usually preferred to correlational studies because they:

have the ability to establish cause-and-effect relationships.

If Dr. Pitt used random assignment in her research, then she can make the reasonable assumption that:

her experimental and control groups have similar characteristics prior to receiving the experimental treatment.

John read with interest a recent newspaper article about a string of murders in his home town. The suspect in the murders has been diagnosed with schizophrenia. John now believes that most mentally ill people are dangerous and should be locked up. John's overestimation of the relationship between mentally ill individuals and aggressive tendencies is referred to as a(n):

illusory correlation.

"Open science" refers to a movement within science to:

increase the number of researchers replicating findings.

Both ________ variables and __________ variables can be classified as scale observations.

interval; ratio ordinal; interval discrete; continuous nominal; ordinal

Including chartjunk on your graph is not advisable because it:

makes it difficult to interpret your data.

What evidence was offered to support the suggestion that cheating occurred on standardized testing in some Chicago Public Schools?

multiple students giving identical, correct answers to the most difficult items on the exam—a statistically unlikely result

A bar graph is appropriate if your independent variable is _____ and your dependent variable is _____.

nominal; scale

If the results from an intelligence test are different when given to the same person on two different occasions, the test is:

not reliable.

In a distribution that is negatively skewed, most of the scores occur _____ of the distribution.

on the right side

One advantage of the _____ is that it allows the user to view two groups in a single graph.

stem-and-leaf plot

The only graph that includes the actual numerical values of a distribution is a:

stem-and-leaf plot.

The interquartile range is a measure of the distance between:

the 25th percentile and the 75th percentile of a data set.

If we flip a coin we would expect the probability of it landing heads is the same as it landing tails (e.g., 0.50). However, we are more likely to achieve this outcome the more often we flip the coin. That is, over a large number of trials we are more likely to approximate our expected probability. This is referred to as:

the law of large numbers.

Imagine that a population of scores is normally distributed. Two samples are drawn from the population—one with a size of 50 and another with a size of 500. Which of the two sample distributions is more likely to be normal in shape?

the one with a sample size of 500

Two events are said to be independent events when:

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

A researcher's decision regarding whether to reject the null hypothesis is based on:

the probability that one would see the observed group differences if there was no effect on the independent variable.

To determine the percentage of scores that fall below a particular score, you first need to convert that person's raw score to a:

z score.

Imagine that you randomly select a sample of 30 newborn infants and find that their mean weight is 8.1 pounds. The population mean of newborn infants is known to be 7.4 pounds with a standard deviation of 1.1 pounds. What would you calculate to compare the mean of this sample to the mean of the population?

z statistic

The mean mathematics score for college-bound seniors who took the SAT in 2013 was 514. If the standard deviation for this same year was 118, what is the z score for a person who received an SAT mathematics score of 650?

+1.15

The critical values associated with a p level of 0.05 for a two-tailed hypothesis test using the z statistic are:

-1.96 and +1.96.

Which of the following groups of scores has the least amount of variability?

10, 8, 7, 7, 10

To what percentile does a z score of -1.0 roughly correspond?

16 percent

If we know the percentage of scores falling between the mean and a z score of +0.50 is 19.15 percent, then what is the percentage of scores falling between the mean and a z score of -0.50?

19.15 percent

To what percentile does a z score of -2.0 roughly correspond?

2 percent

A graduate statistics class is unhappy with midterm grades. The professor will curve the grades only if the class figures out how much the curve needs to be for the mean score to equal 85. What should the curve for the class be if these are the midterm scores for class members: 72, 88, 95, 76, 69, 71, 81, 80, 73, and 85?

6 points

The quantitative subtest of the Graduate Record Exam (GRE) has a mean of 500 and a standard deviation of 100. What GRE score would correspond to a z score of 1.50?

650

What is the primary difference between descriptive and inferential statistics?

Descriptive statistics are better able to control confounding variables than inferential statistics. Inferential statistics typically have greater reliability than descriptive statistics. Inferential statistics typically involve larger amounts of data than descriptive statistics. Inferential statistics allow researchers to draw conclusions about populations while descriptive statistics simply organize and summarize data.

What does it mean that the normal curve is symmetric?

Exactly 50 percent of scores fall below the mean and 50 percent fall above the mean.

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?

The mean of the deviations balances out to zero due to negative and positive values.

Suppose a distribution of exam scores included six people with a score of 50. How would this be represented on a stem-and-leaf plot?

The number 5 would be followed by the number 0 repeated six times.

Paula attempts to replicate a classic finding in psychology. Her study, however, does not yield the same results. What should she conclude?

The original finding may be flawed, but her replication could be flawed as well. Additional replications are necessary.

A researcher is interested in the effects of sleep deprivation on memory. Assume that memory (the dependent variable) is always measured the same way—as the number of items recalled on a standard memory test (i.e., this is a scale variable). However, the independent variable could be manipulated in a number of different ways. For which of the options below would a line graph or scatterplot be most appropriate?

The researcher records the number of hours that each person sleeps.

Joline is a kindergarten teacher who is interested in calculating the variability in the number of sight words remembered by the 32 students in her class. What is the best measure of variability in this situation?

The standard deviation, because it uses all of the scores in the data set and is easy to interpret

What type of error could be made if we reject the null hypothesis?

Type I

Early research indicated that vitamin E could enhance exercise performance. However, more recent and better designed studies led to the conclusion that vitamin E has no exercise benefits. The early, incorrect conclusions were probably the result of:

Type I errors.

A _____ error is considered to be worse than a _____ error because it is more likely to lead people to action.

Type I; Type II

A nurse at a local hospital records the number of male babies and the number of female babies born during the month of August. Should he create an ungrouped or grouped frequency table to represent the data?

Ungrouped, because there are only two values on the x-axis

What is the difference of the denominator of the equation for the z score and that for the z statistic?

When computing a z score, you divide by the population standard deviation, but when computing a z statistic, you divide by the standard error of the sampling distribution.

In an analysis by Sterne and Smith (2001) it was estimated that _____ of published medical studies exhibit Type I errors.

almost half

As sample size increases, the shape of the sample distribution of the mean:

becomes narrower.

A(n) _____ is a level of the independent variable that does not receive the treatment of interest in a study.

control group

A Type I error occurs whenever a(n):

correct null hypothesis is rejected.

As sample size increases, the standard error:

decreases

A(n) _________ variable meets the criteria for either an interval variable or a ratio variable.

dependent independent discrete scale

Two basic branches of statistics are ______ and _______.

dichotomous; continuous independent; dependent sample; population descriptive; inferential

The _______ lie can occur when we assume that a pattern of data will continue indefinitely.

extrapolation

Juanita bought a chain of video rental stores in the late 1990s and business was very strong for a couple of years. The number of video rentals was increasing yearly and she was very confident that it would continue indefinitely. However, she did not foresee the rise of video on-demand and consequently her business has been in a slow decline for the past several years. Juanita's assumption that the upward trend in video rentals would continue could be referred to as a(n):

extrapolation lie.

In a research study it is important to specify exactly how we will measure the variables that will be studied. In other words, it is important that we use:

operational definitions.

Suppose that, as part of a larger survey, we measure the variable "year in school." The variable has the possible values of freshman, sophomore, junior, or senior. These possible values are called:

operational definitions. levels or conditions. variables. confounds.

The numbers on athletes' uniforms are an example of a(n) _____ variable.

ordinal nominal ratio interval

In studying the results of his most recent exam, Professor Simmons noticed that although almost all students got between 65 percent and 80 percent on the exam, one student answered 98 percent of the questions correctly. Scientists refer to this type of extreme data as a(n):

outlier

Extreme scores that are either very high or very low in comparison with the rest of the scores in the sample are referred to as:

outliers

If you wanted to compare levels on a bar graph, a ________would be the easiest to use.

pareto chart

In a pie chart, each slice represents the _____ of each category.

percentage

When depicting portions or percentages on a nominal variable with few levels the best option would be a:

pie chart

College students at 50 campuses around the country were polled to find out how many students own smartphones. This small representative group of students is called a:

population. sample. mode. median.

A residential neighborhood of several modestly priced homes is undergoing a transformation. Recently, a few very expensive homes have been built in the area. If we created a frequency distribution of home values in the neighborhood, what would it look like?

positively skewed

The p level is the:

probability with which a test statistic would occur if the null hypothesis were true.

In a study designed to measure the effects of exercise on weight loss, participants are randomly assigned to either an exercise or a no-exercise group. Most of the participants in the exercise group lost weight but one participant gained weight. A researcher may be interested in analyzing this extreme data because it may:

provide insight into factors that influence the dependent variable.

If we made sure that each of our participants has an equal chance of being assigned to any condition in an experiment, we would be using:

random assignment.

Bar graphs are highly informative, but they can also be deceiving because what seems to be a significant difference in means may actually be a small difference. What part of the graph reveals if a difference in means is exaggerated?

range of values on the y-axis

A _______ provides more information by eliminating the axes below the minimum value and above the maximum value.

range-free

The _____ hypothesis assumes that there is a difference between populations.

research

Which of the following partially explains the relatively high rate of Type I errors?

the tendency of journals to publish "exciting" findings—that is, ones that report positive outcomes.

The symbol N represents:

the total number of scores in a sample.

When drawing a graph, the dependent variable normally belongs on:

the vertical or y-axis.

The null hypothesis states that:

there are no differences between the populations we are studying.

Unnithan, Houser, and Fernhall (2006) were interested in whether playing the game Dance Dance Revolution (DDR) affected the heart rate of overweight adolescents differently than it did non-overweight adolescents. Twenty-two adolescents, 10 classified as overweight and 12 as not overweight, played DDR for 12 minutes while the researchers measured each participant's heart rate. On average, the researchers found no difference between the heart rate of the two groups. The hypothesis test for this study is:

two-tailed.

There are three defining characteristics of the normal curve. These are:

unimodal, symmetric, and defined mathematically.

If we believe we are creating a measure of personality but in fact it measures intelligence, we would say that our measure lacks:

validity. levels. reliability. consistency.

Students who post responses on ratemyprofessor.com are what kind of sample?

volunteer

The graph in your text comparing the cost of higher education with the quality of education at Cornell University was used to illustrate:

ways that graphs can be misleading.

In a hypothesis test, a z statistic that is less extreme than the critical values indicates that:

we don't have enough evidence to support the research hypothesis.

Under what conditions is it permissible to proceed with a hypothesis test, even though the assumption that the dependent variable is measured on a scale measure is violated?

when the data are not clearly nominal or ordinal

Under what conditions is it permissible to proceed with a hypothesis test, even though the assumption that participants are randomly selected is violated?

when you are cautious about generalizing your results