PY211 Exam 1 and 2 MC Questions

Which of the following statements regarding the null hypothesis is true?

The null hypothesis always makes statements about a population parameter.

Which of the following is the best explanation for why the standard deviation is almost always reported with the mean?

The standard deviation measures the spread of scores from the mean, so it is important to know both the mean and the standard deviation.

A researcher computes a test statistic and finds that the p value for this test is .03. What does this result mean?

There is a 3% likelihood of obtaining the test statistic value, if the null were true.

Given the same set of data for a population and sample, would the mean for both data sets be equal?

Yes, this would be true anytime both data sets are the same.

A sampling distribution of the sample mean or variance is ________.

a distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population

A professor compared differences in class grades between students in their freshman, sophomore, junior, and senior years of college. If different participants were in each group, then what type of statistical design is appropriate for this study?

a one-way between-subjects ANOVA

A distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population is called ______.

a sampling distribution

In a normal distribution, 50% of all data ______.

all of these

Following a significant one-way between-subjects ANOVA in which k > 2, what is the next appropriate step?

conduct post hoc tests

When reporting the results of a one-sample z test using APA format, the ______ does not need to be reported.

critical values

Computing a one-way between-subjects ANOVA is appropriate when ______.

different participants are observed one time in each of two or more groups for one factor

A health practitioner measures the heart rate (in number of beats per minute) of patients under low, moderate, and high stress levels. Heart rate can be best described as ______.

discrete data

Which of the following requires the calculation of a real range?

frequency distributions for grouped data

A graphical display for grouped frequency distributions with continuous data is called a ______.

histogram

A researcher measures the weight (in ounces) of newborn infants in the month of March. What type of graphical display would be most appropriate for summarizing the frequency of infants falling into different intervals of weight?

histogram

A researcher asks a sample of brothers and sisters to rate how positive their family environment was during childhood. In this study, the differences in ratings between each brother and sister pair were compared. The type of design described here is called a ______.

matched-samples design

Which of the following describes a descriptive statistic?

summarize

A researcher identifies college students as a group of interest to test her hypothesis. She then identifies a few local college students and selects a small group of the local college students to be observed. In this example, the sample is ______.

the small group of college students who here observed

The normal distribution has all of the following characteristics, except that ______.

the total area under the curve is greater than 1.0

A researcher obtains z = 1.45 for a one-sample z test. What is the decision for this test at a .05 level of significance?

to retain the null hypothesis

A researcher compares differences in mean health scores between students at two local high schools. Assuming that the population variance is unknown, what type of t test is appropriate for this study?

two-independent-sample t test

A researcher conducts a study measuring differences in brain activity among rats placed on either a continuous or intermittent reward schedule. Assuming that the population variance in unknown, what t test is appropriate for this study?

two-independent-sample t test

A researcher records the following data for how participants rated the likability (on a scale from 1 = not liked at all to 7 = very likable) of an individual who blushed after making a mistake: 5, 4, 7, 6, 6, 4, 6, 7, 2, 5, and 6. Is the mode equal to the median in this example?

yes

A researcher records the level of attention among 18 students during an interactive and lecture portion of a single class. If she computes a related-samples t test at a .05 level of significance (two-tailed test), then what are the critical values for this test?

±2.110

A researcher conducts a study in which k = 4 and n = 22 in each group. What are the degees of freedom for the one-way between-subjects ANOVA?

(3, 84)

A researcher finds that 12% of participants make between three and five visits to a physician each year. What are the real limits for this interval?

2.5-5.5

Which of the following distributions has the largest variability?

1, 3, 6, 9, and 12

A researcher measures the amount of coffee consumed by college students while studying during the final exam week. In her study, she found that students drink 2.3 ± 0.8 (M ± SD) cups of coffee per study session. Assuming the data are normally distributed, which of the following is the most appropriate conclusion?

Most students drink between 1.5 and 3.1 cups of coffee per study session.

The size of a population is symbolized as ______, whereas the size of a sample is symbolized as ______.

N; n

Suppose that a researcher is interested in a group of 10 million people who paid to see a movie playing in theaters. In this example, the 10 million moviegoers would be regarded as ______.

a population of moviegoers who paid to see the movie in a theater

One difference between a repeated-measures design and a matched-samples design is that ______.

only one design involves observing the same participants in each group

A movie critic ranks a movie on a scale from 1 (lowest) to 4 (highest) stars. What scale of measurement are the ratings?

ordinal

Suppose you select a sample of three people from a population of four (A, B, C, D). Which of the following samples is possible using the experimental sampling strategy?

persons B, C, and D

a psychologist reviews her notes for all her patients and determines that on average her patients complete therapy in 24 days. The average time to complete therapy among all her patients is called a(n) ______.

population parameter

In hypothesis testing, a researcher can never ______.

prove that his or her hypothesis is correct

A researcher assigns 21 adolescents to rate the likability of a person described in a vignette as having one of three personality traits. An equal number of participants are assigned to each group. If mc005-1.jpg = 4.08 for this study, then what was the decision at a .05 level of significance for a one-way between-subjects ANOVA?

reject the null hypothesis

A professor compares scores on a competency exam among students at two times during a single semester. What type of t test is most appropriate for this study?

related-samples t test

A researcher compares the difference in the amount of texting by students in class during the first week and last week of classes. The type of design described here is called a ______.

repeated-measures design

The ______ is an inferential statistic used to determine the number of standard deviations in a t distribution that a sample mean deviates from the mean value or mean difference stated in the null hypothesis.

t statistic

A key difference between a t statistic and a z statistic is that the standard error is ______ to compute a t statistic.

estimated

The range of scores between the upper and lower quartiles of a distribution is called the ______.

interquartile range

State the critical value(s) for a t test using a two-tailed test at a .05 level of significance: t(20).

+-2.086

A researcher computes a one-way within-subjects ANOVA in which k = 3 and n = 10. What is the critical value for this test at a .05 level of significance?

3.55

A researcher records the time in seconds it takes a sample of participants to walk alone through a dark portion of campus. The researcher computes SS = 1,200. Assuming that a sample of 25 participants was observed in this study, what is the standard deviation for these data?

7.1 s

How is the sample variance computed differently from the population variance?

The calculation in the denominator is different.

A researcher notes that the variability attributed to difference between group means is quite large. Which source of variation is the researcher referring to?

between-groups

A type of factor in which different participants are observed in each group, or at each level of the factor, is called ______.

between-subjects factor

A researcher reports that the mean time it takes to complete an experimental task is 1.4 ± 8.0 (M ± SD) s. If the null hypothesis was that the mean equals 1.0, then what is the effect size for this test using estimated Cohen's d?

d = 0.05; small effect size

A researcher reports that mean ratings of liking for some food are 0.8 ± 2.4 (M ± SD). If the null hypothesis was that the mean equals 0, then what is the effect size for this test using estimated Cohen's d?

d = 0.33; medium effect size

State the four scales of measurement in order from least informative to most informative.

nominal, ordinal, interval, ratio

A researcher reports that the size of an effect in some population is d = 0.88. Which of the following is an appropriate interpretation for d?

Mean scores shifted 0.88 standard deviations in the population.

A researcher records the following response times to a visual stimulus: 23 ± 3.1 (M ± SD) seconds. Assuming these data are normally distributed, what is the probability that participants responded in 20 s or less?

.1660

A researcher records a sample of 30 exam scores and finds that if these data were treated as a population, that the population variance calculation for these data is larger than the sample variance calculation for these same data. Is this outcome for variance possible?

No, the sample variance will be larger because SS is divided by degrees of freedom in the denominator of the variance formula.

Two normal distributions are observed. The first distribution has a mean of 12 and a standard deviation of 2. The second distribution has a mean of 0 and a standard deviation of 2. For which distribution will the z score for the mean be larger?

None, the z score will be the same

As sample size increases, the standard error of the mean ______.

decreases

Statistical analysis allows researchers to ______.

evaluate scientific observations

An article states that a sample of 40 participants took 12 ± 2.3 (M ± SEM) s to complete a cognitive assessment. Which value is the standard error of the mean?

2.3

A researcher selects a sample of 100 participants from a population with a mean of 38 and a standard deviation of 20. About 68% of the sample means in this sampling distribution should be between a sample mean of ______.

36 and 40

"Elementary school children spent significantly more time reading the presence of a teacher than when the teacher was absent, t(7) = 2.804, p < .05 (o^2=?4 0.46)." In this related-samples t test, how many participants were observed?

8

What does it mean to say that the sample mean is an unbiased estimator of the population mean?

If we select a sample at random, then on average we can expect the sample mean to equal the population mean.

Which characteristic of a histogram implies that it summaries continuous data?

The vertical bars touch at the upper boundary of each interval.

A researcher randomly selects a sample of athletes and reports that their average score on a health and fitness scale is 23. Based on the characteristics of the sample mean, what does this say about the mean in the population?

We expect that the population mean is equal to 23 because the sample mean is an unbiased estimator of the population mean.

Regardless of the distribution of the population, the sampling distribution of sample means will be approximately normally distributed. What characteristic of the mean explains this?

central limit theorem

A researcher finds that the average preschool-aged child drinks two cups of milk per day. Assuming these data are normally distributed, the z score for the average cups per day in this example is ______.

exactly equal to 0

A researcher tests whether the dosage level of some drug (low, high) causes significant differences in health. To do this, the researcher randomly assigns rat subjects to receive a low or high dosage of the drug and records health-related measures in both groups. The type of method described is ______.

experimental

A therapist observes that spouses are more likely to forgive their partners for lying to them if they find out the truth from their spouse and not a third party. In this example, the dependent variable is ______.

forgiveness

Procedures that allow researchers to infer or generalize observations made with samples to the larger population from which they were selected best describes ______.

inferential statistics

Grouped data are distributed into ______, whereas ungrouped data are distributed into ______.

intervals; categories

______ data describe numeric aspects of phenomena; whereas ______ data describe nonnumeric aspects of data.

quantitative; qualitative

A researcher conducts two t tests. Test 1 is a two-tailed test with a smaller sample size at a .05 level of significance. Test 2 is a two-tailed test with a larger sample size at a .05 level of significance. What do you know about the degrees of freedom for each test?

test 2 is associated with larger degrees of freedom

Regardless of the number of scores in a distribution, the range only includes ______ score(s) in its calculation

two

The t distribution is similar to the z distribution except ______

(all of these) a. it is associated with greater variability b. it is characterized by "thicker" tails compared with the z distribution c. it is associated with scores being more likely in the tails of the distribution

In terms of characterizing samples, statistical theory was developed using a sampling strategy in which ______.

(all of these) a. the order of selecting participants matters b. the same participant can be selected twice in the same sample c. participants are replaced after being sampled