STAT Final Exam
Parameter
Data about a population
a researcher determines that students study an average of 80 +/- 20 (M+/-SD) minutes per week. assuming these data are normally distributed, what is teh z score for students studying 60 minutes per week? a) 1.0 b) -1.0 c) .3413 d) .1587
b) -1.0
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. In this related samples t test, how many participants were observed? a) 5 b) 6 c) 7 d) 8
d) 8
in a normal distribution, 50% of all data: a) fall above the mean b) fall below the median c) fall above or below the mode d) all of the above
d) all of the above
the criteria for a decision regarding the value stated in a null hypothesis is set by the a) level of significance b) p value c) probability value d) both a and b
d) both a and b
for the following distribution, what is the highest score? x f 20-25 2 15-19 5 10-14 4 5-9 1 a) 5 b) 20 c) 25 d) cannot be determined
d) cannot be determined
State the critical values for a t test using a two-tailed test at a .05 level of significance a) +/- 1.725 b) +/- 2.093 c) +/- 2.086 d) +/- 0.687
c) +/- 2.086
what is the value of SS (sum of squares) for the following population? 1, 1, 1, 5 a) 3 b) 7 c) 12 d) 28
c) 12
a researcher records the following times (in seconds) that it took a group of students to complete an exam: 18+/- 2 minutes. How long did it take 80% of students to complete the exam? a) less than 16 minutes b) 16.32 minutes c) less than 18 minutes d) 19.68 minutes
d) 19.68 minutes
_______________ allows researchers to describe 1) how far mean scores have shifted in the population, or 2) the percentage of variance that can be explained by a given variable. a) significance b) probability c)power d) effect size
d) effect size
The use of tables and graphs to summarize data is an example of A) inferential statistics B) Interpretation C) Descriptive statistics D) Generalization
C) Descriptive Statistics
Statistic
Data about a sample
a researcher selects a sample of 25 participants from a population with a mean of 10 and a standard deviation of 5. what is the probability of selecting a sample mean that is atl east two standard deviations larger than the population mean? a) .0228 b) .4772 c) .9772 d) equal to the probability of selecting a sample mean that is at least two standard deviations below the mean
a) .0228
what is the typical level of significance for a hypothesis test in behavioral research? a) .05 b) .10 c) .001 d) .50
a) .05
Fill in the missing values for a and b in this frequency distribution table Intervals Frequency 6.0-6.6 12 5.3-5.9 7 4.6-5.2 B 3.9-4.5 10 A-3.8 8 a) A=3.2 , B= 13 b) A = 3.1 , B = 14 c) a = 3.3 , B = 13 d) there is not enough information to complete this table
a) A= 3.2, B= 13
A researcher records the number of distractors (such as noises) that preschool-aged children ignore while watching a popular Sunday morning cartoon show. Assuming that the population variance is unknown, what type of t test is appropriate for this study? a) one-sample t test b) two-independent sample t test c) there is not enough information to answer to question
a) one-sample t test
Recording whom students study with describes ________ types of data; whereas recording the number of hours spent studying per week describes ________ types of data. a) qualitative; quantitative b) continuous; discrete c) quantitative; qualitative d) discrete; continuous
a) qualitative; quantitative
a measure of the average squared distance of scores from the mean is called the a) range b) IQR c) variance d) sum of squares
c) variance
A researcher distributes frequencies into the following classes: absent, tardy, present. What type of data are distributed? a) nominal data b) qualitative data c) ungrouped data d) all of the above
d) all of the above
a simple frequency distribution a) can be used to summarize grouped data b) can be used to summarize ungrouped data c) summarizes the frequency of scores in a given category or range d) all of the above
d) all of the above
A professor finds that the average SAT score among all students attending his college is 1150+/-150. He polls his class of 25 students and finds that the average SAT score is 1200. Suppose he computes a one-sample z test at a .05 level of significance. What is his decision? a) to reject the null hypothesis b) to retain the null hypothesis c) to reject the null hypothesis for a two-tailed test, but to retain the null hypothesis for an upper-tailed test d) to reject the null hypothesis for an upper-tailed test, but to retain the null hypothesis for a two-tailed test
d) to reject the null hypothesis for an upper-tailed test, but to retain the null hypothesis for a two-tailed test
Non-parametric tests
Do not make inferences about a population: any type of distribution; nominal and ordinal
Parametric tests
Make inferences about a population based on our sample, normally distributed; ratio and interval data
A researcher reports that the mean difference in response time to an auditory versus a visual cue is 0.83 seconds, with a pooled sample variance equal to 2.45. What is the effect size for this test using estimated Cohen's d? a) d=0.53; medium size effect b) d = 0.53; large effect size c) d = 0.34; small effect size d) d = 0.34; medium effect size
a) d=0.53; medium size effect
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 a) experimental b) quasi-experimental c) correlation d) operational
a) experimental
Interval scales of measurement a) have equidistant scales b) have a true zero c) both a and b d) none of the above
a) have equidistant scales
a graphical display for grouped frequency distributions with continuous data is called a a) histogram b) bar chart c) pie chart d) scatter gram
a) histogram
______________ is the variable in an experiment that is manipulated between conditions being observed a) independent variable b) quasi-independent variable c) dependent variable
a) independent variable
Procedures that allow researchers to infer or generalize observations made with samples to the larger population from which they were selected best describes a) inferential statistics b) sample statistics c) descriptie statistics d) population parameters
a) inferential statistics
a researcher believes that increasing attention given to children will improve mean academic performance. therefore, the alternative hypothesis should be: a) mean academic performance will increase b) mean academic performance will increase c mean academic performance will not chance d) mean attention will increase
a) mean academic performance will increase
an animal researcher measures the number of times a rat presses a lever located a t the right center and left of a cage for a food reward. what scale of measurement is the location of lever pressing? a) nominal b) ordinal c) interval d) ration
a) nominal
an education counselor records the number of high school graduates enrolled in community colleges, four-year colleges, and universities. What scale of measurement is the type of college? a) nominal b) ordinal c) interval d) ratio
a) nominal
a type of related samples design in which participants are observed more than once is called a) repeated measures design b) matched pairs design c) matched samples design d) both B and C
a) repeated measures design
a researcher measures the number of trials it takes two samples of participants to master a new task. In both samples, SS=240. sample A consists of 12 participants and Sample B consists of 18 participants. Which sample is associated with the largest variance? a) sample a b) sample b c) both samples have the same variance d) there is not enough information to answer this question
a) sample A
researchers measure data in a ___________ to learn more about individuals in the larger ______________ of interest. a) sample; population b) statistic; inference c) population ; sample d) inference; statistic
a) sample; population
Based on the effect size conventions, d = .18 is a a) small effect b) medium effect size c) large effect size
a) small effect size
a researcher conducts an experiment to determine whether moderate doses of st. John's Wort have any effect on memory for college students. For this study what is the independent variable? a) the amount of st. johns wort given to each participants b) the memory score for each participant c) the group of college students d) cannot answer without more information
a) the amount of st. johns wort given to each participant
Using APA format, which value is typically given in parentheses when reporting the results for a t test? a) the degrees of freedom b) the estimate for standard error c) The value of the test statistic d) the level of significance
a) the degrees of freedom
The mean crying time of infants during naptime at a local preschool is 12 minutes. the school implements a new naptime routine in a sample of 25 infants and records an average crying time of 8+/- 4.6 minutes. Test whether this new naptime routine reduced crying time at a .05 level of significance a) the new naptime routine significantly reduced crying time, t(24) = -4.35, p<.05 b) the new naptime routine did not reduce crying time, t(t24) = -4.35, p <.05 c) The new naptime routine did not reduce crying time, t(24) = .92, p >.05 d) the new naptime routine significantly reduced crying time, t(24) = .92, p<.05
a) the new naptime routine significantly reduced crying time, t(24) = -4.35, p<.05
A student scores in the 80th percentile on an exam. What does this mean in comparison to all other students? a) the student scored higher than 80% of all others who took the exam b) the student scored worse than 80% of all others who took the exam c) of all those who took the exam, only 80% of them completed it d) the student would score the same grade on teh exam 80% of the time
a) the student scored higher than 80% of all others who took the exam
a researcher records the following data for how participants rated the likability (on a scale of 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? a) yes b) no; the median is larger than the mode c) no; the mode is larger than the median d) there is not enough information to answer the question
a) yes
a researcher records the following data for the number of dreams recalled during a night of sleep for 10 college students: 3, 2, 4, 4, 3, 1, 1, 0, 2, 0. Is the mean equal to the median in this example? a) yes b) no; the median is larger than the mean c) no; the mean is larger than the median d) there is not enough information to answer this question
a) yes
A researcher matched 30 participants on intelligence (hence 15 pairs of participants), and then compared differences in emotional responsiveness to two experimental stimuli between each pair. For this test, what are the critical values, assuming a two-tailed test at a .05 level of significance? a) +/- 2.042 b) +/- 2.045 c) +/- 2.131 d) +/- 2.145
b) +/- 2.045
What is the z score for scores in the top 2.5%? a) .675 b) 1.96 c) .0124 d) .0250
b) 1.96
A researcher states that a sample of 100 shoppers spend 112 +/- 40 dollars on groceries each week. which value is the standard error fo the mean? a) 112 b) 40 c) 100 d) the standard error fo the mean is not reported in the article
b) 40
A researcher records the following assessment data: 42 +\- 6. The researcher only wants to sample participants scoring in the top 20% of this assessment. What is the cutoff score for the top 20% in this example? a) 0.84 b) 47.04 c) 36.96 d) There is not enough information to answer this question
b) 47.04
for the same distribution shown in question 32, how many people had scores greater than x = 14? x f 20-25 2 15-19 5 10-14 4 5-9 1 a) 5 b) 7 c) 11 d) cannot be determined
b) 7
A researcher selected a sample of 24 participants and observed their behavior at two times. The result of a related samples t test at a .05 level of significance was t = 2.68. Which of the following correctly describes the result of this test? A) a related samples t test is the correct test fo r this study; the result of the test is not significant b) a related samples t test is the correct test for this study; the result of the test is significant c) the result of the test cannot be appropriately interpreted because the related samples t test was not the correct test for this study; the researcher should have computed a two-independent sample t test d) the result of the test cannnot be appropriately interpreted because the related samples t test was not the correct test for this study; the researcher should have computed a one-sample t test
b) a related samples t test is the correct test for this study; the result of the test is significant
as sample size increases, the standard error of the mean a) increases b) decreases c) can increase or decrease d) does not change
b) decreases
A researcher records the number of votes for each of five candidates running for class president. Based on her presentation of the following results, what type of statistics did she use? Candidate Number of Votes A 120 B 125 C 42 D 203 E 20 a) inferential statistics b) descriptive statistics c) population statistics d) deceptive statistics
b) descriptive statistics
The test statistic for a related samples t test makes tests concerning a single sample of a) raw scores b) different scores c) participant scores d) original data
b) different scores
A researcher has participants rate the likability of a sexually promiscuous person described in a vignette as being male (n=20) or female (n=12). The mean likability ratings in each group were 4.0. if the null hypothesis is that there is no difference in likability ratings, then do likability ratings differ at a .05 level of significance? a) yes, this result is significant, p<.05 b) no, this result is not significant, t(30) = 0 c) No, this result is not significant, t(30) = 1.00 d) there is not enough information to answer this question, because the variance in each sample is not given
b) no this result is not significant t(30) = 0
A researcher selects a sample of 36 students from a school population with a mean IQ of 100 and a standard deviation of 12. She found that the mean IQ in this sample is 104. Assuming she conducts a one-sample z test at a .05 level of significance, what is the decision for a two-tailed test? a) retain the null hypothesis; IQ scores in this sample are the same as those in the population b) reject the null hypothesis; IQ scores in this sample are significantly higher than those in the population c) there is not enough information to make a decision
b) reject the null hypothesis; IQ scores in this sample are significantly higher than those in the population
A researcher tests how well participants know their spouse while under hypnosis, and again without hypnosis. It was hypothesized that participant responses would be more accurate (greater number of correct responses) when under hypnosis. The mean number of correct responses was M = 5.30 under hypnosis and M = 3.40 without hypnosis in a sample of 30 participants. If the estimated standard error for difference scores was 2.52, then what is the decision at a .05 level of significance (two-tailed test)? a) retain the null hypothesis; responses were more accurate under hypnosis b) retain the null hypothesis; responses were not more accurate under hypnosis c) reject the null hypothesis; responses were more accurate under hypnosis d) reject the null hypothesis; responses were not more accurate under hypnosis
b) retain the null hypothesis; responses were not more accurate under hypnosis
A characteristic (usually numeric) that describes a sample is called a a) sample b) sample statistic c) population d) population parameter
b) sample statistic
which of the following best describes a dependent variable? a) the sample variable b) the measured behavior c) the manipulated variable d) the population variable
b) the measured behavior
Which proportion is largest in a z distribution? a) the proportion of area above the mean b) the proportion of area betwen z = +1 and z = -1 c) the proportion of area above z = 1.0 d) the proportion of area below z = 0
b) the proportion of area between z = +1 and z + -1
Given the following values: M=6.0, X-Bar=7.6, n=36, and O=6, conduct a one-sample z test at a .05 level of significance. for a one-tailed test, upper-tail critical, what is the decision? a) to reject the null hypothesis b) to retain the null hypothesis c) there is not enough information since the sample size is not given
b) to retain the null hypothesis
a researcher obtains z = -6.45. what is the decision for a one-tailed test, upper-tail critical, at a .05 level of significance? a) to reject the null hypothesis b) to retain the null hypothesis c) it depends on the sample size d) there is not enough information to make a decision
b) to retain the null hypothesis
A counselor records the number of disagreements (per session) among couples during group counseling sessions. If the number of disagreements is distributed normally as 4.4 +/- 0.4 (M + SD) disagreements, then what proportion of couples disagree at least 4 times during each counseling session? a) .3413 b) .1587 c) .8413 d) the probability is not listed in the unit normal table
c) .8413
a psychologist treats 16 patients and records the number of sessions required to complete a behavioral therapy treatment for each patient. she computes SS = 800. assuming the 16 patients constitute all patients under her care ( so the population of her patients), what is the standard deviation for these data? a) 53.3 sessions b) 50 sessions c) 7.1 sessions d) 7.3 sessions
c) 7.1 sessions
A professor records the following final exam scores: 78 +/- 7. Students scoring in the top 14% get an A. What is the cutoff score for the top 14% in this example? a) 1.08 b) 70.44 c) 85.56 d) there is not enough information to answer this question
c) 85.56
a researcher records the sound (in decibels) during a series of lessons taught by a substitute teacher at a local elementary school. in this study, he found that the sound was 80+/-6 (M+/-SD) decibels. assuming the data are normally distributed, which of the following is an appropriate conclusion? a) 68% of classes were between 68 and 80 decibels b) 5% of classes were louder than 68 decibels c) 95% of classes were between 68 and 92 decibels d) all of the above
c) 95% of classes were between 68 and 92 decibels
a professor gives an exam in which the mean score is 78 points. she gives another exam to test whether or not scores change. in this example, the null hypothesis is a) M=/=78 b) x=/=78 c) M = 78 d) x = 78
c) M = 78
The average response time to a bank robbery is about 9 minutes. A local community wants to improve on this time, so they implement advanced training seminars. They find that the new response time for a sample of 36 police officers is 8 +\-4.2 minutes. Test whether this advanced training seminar reduced response time at .05 level of significance. a) This advanced training seminar significantly reduced response time, t(35) = 11.43, p<.05 b) This advanced training seminar significantly reduced response time, t(35) = -1.43, p<.05 c) This advanced training seminar did not significantly reduce response time, t(35) = -1.43 p>.05 d) There is not enough information to answer this question
c) This advanced training seminar did not significantly reduce response time, t(35) = -1.43 p>.05
most behavior is believed to __________ a normal distribution. a) be exactly equal to b) not resemble at all c) approximate
c) approximate
the procedure of converting a categorical variable to numeric values is called a) deteriorating b) piloting c) coding d) constructing
c) coding
the sample variance is computed by dividing SS by ________; whereas the population variance is computed by dividing SS by _____. a) N; df b) df; n-1 c) df; N d) n-1; df
c) df; N
A method for testing a claim or hypothesis about a parameter in a population, using data measured in a sample, is called a) random sampling b) level of significance c) hypothesis testing d) guessing
c) hypothesis testing
a researcher measures the body temperature (in degrees of Farenheit) of participants immediately before and immediately following sleep. Temperature is on what scale of measurement? a) nominal b) ordinal c) interval d) ratio
c) interval
a researcher randomly selects a sample of participants from a population with a variance of 4. if a researcher selects a sample of 16 participants with a mean of 12, then what is the mean and standard error for the sampling distribution of the mean? a) mean = 12 , standard error = 2 b) mean = 12, standard error = 1 c) mean = 12, standard error = 0.5 d) there is not enough information to answer this question
c) mean = 12, standard error = 0.5
a researcher asks adult participants to rank their top five favorite songs from their childhood. based on the scale of measurement described, which measure of central tendency is most appropriate to describe these data? a) mean b) median c) mode d) range
c) mode
A researcher selects two samples of 25 participants each. The first sample is from the population where the population mean was 32 and the variance was 8. The second sample is from the population where the population mean was 4 and the variance was 8. Which sample will be associated with a larger standard error of the mean? a) sample 1 b) sample 2 c) none, both samples will have the same value for standard error d) there is not enough information to answer this question
c) none, both sample will have the same value for standard
Three key elements of control that allow researchers to draw cause-and-effect conclusions a) randomization, manipulation, and variation b) assignment, manipulation, and comparison/control c) randomization, manipulation, and comparison/control d) randomization, condition, and comparison/control
c) randomization, manipulation, and comparison/control
to determine the interval width, we divide the ________ by the number of intervals a) observed range b) exclusive range c) real range d) all of the above
c) real range
A researcher conducts a study and concludes that a new behavioral health treatment program significantly reduces one's risk for disease compared with risk levels in the general population (d = -0.64). Interpret the size of this effect a) 64% of the variability in risk level can be accounted for by the new treatment b) 64% of the new treatment can be accounted for by the risk levels c) risk levels in the population shifted 0.64 standard deviations below the mean d) risk levels in the population shifted 0.64 standard deviations above the mean
c) risk levels in the population shifted 0.64 standard deviations below the mean
state the problem with this frequency distribution Intervals Frequency 8-10 4 6-8 7 4-6 3 2-4 6 0-2 9 a) the interval width is too small b) the interval width is unequal c) the class intervals overlap d) the number of intervals is too small
c) the class intervals overlap
If the value of the test statistic is in the rejection region, then a) p<.05 b) the decision is to reject the null hypothesis c) the value of the test statistic is larger than the critical value d) all of the above
d) al of the above
computing a one-sample t test is appropriate when a) participants are assigned to only one group b) the population variance is unknown c) participants are observed one time d) all of the above
d) all of the above
a researcher selects a sample of 25 participants from a population with a mean of 10 and a standard deviation fo 5. what is the probability of selecting a sample mean equal to at least 12? a) less than 1% b) greater than 50% c) about the same as selecting a sample mean that is at least equal to the population mean d) equal to the probability of selecting a sample mean that is smaller than 8
d) equal to the probability of selecting a sample mean that is smaller than 8
a researcher selects a sample of 25 participants from a population with a mean of 10 and a standard deviation of 5. what is the probability of selecting a sample mean equal to at least 12? a) less than 1% b) greater than 50% c) about the same as selecting a sampole mean that is at least equal to the population mean d) equal to the probability of selecting a sample mean that is smaller than 8
d) equal to the probability of selecting a sample mean that is smaller than 8
three research methods common to research in the behavioral sciences are a) experimental, transferable, and correlation b) experimental, variable, and correlational c) experimental, operational, and quasi-correlational d) experimental, quasi-experimental, and correlational
d) experimental, quasi-experimental, and correlational
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 a) not clearly identified b) all college students c) a few local college students d) the small group of college students who were observed
d) the small group of college students who were observed
Researchers rarely have access to entire populations. How do researchers resolve this limitation? a) they do not resolve this; it is not a limitation at all b) they record data from an entire population of people to make inferences concerning characteristics in a sample c) they record data from as many persons in a population as possible to draw conclusions concerning only those individuals d) they record data from a sample of people in the larger population in order to make inferences concerning characteristics in that larger population
d) they record data from a sample
the unit of measurement distributed along the horizontal axis of a standard normal distribution is referred to as a) raw score b) x-score c) normalized deviation d) z-score
d) z-score
