Item Bank Worksheet Ch 9,10,11 stats- PY 211

a researcher selected a sample of 24 participants and observed their behavior at two times. the results of a related samples t test at a .05 level of significance was t=2.68. which one of the following correctly describes the results of this test?

a related sampled t test is the correct test for the study; the results of this test are significant

which of the following is the denominator of the test statistics for the related samples t test? a) standard error b) estimated standard error c) estimated stranded error for the difference d) estimated standard error for the difference scores

d

all other things being equal, increasing the sample size will___ the value of the test statistic for a related sample t test?

increase

a researcher concludes that stress levels are higher following a major versus a minor traffic accident (95% confidence interval 1.86-3.02) if the null hypothesis stated that there would be no difference then what is the effect size for this confidence interval?

ratings of stress shifted between 1.86 and 3.02 points in the population

if the null hypothesis is outside the CI, then the decision was likely to _____ using hypothesis testing

reject the null hypothesis

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

repeated measures design

a researcher compares the height of male executives in the US to the average height of males (mu = 67) he determines that the average hight of male executives is 70 inches (CI 68-72) based on this result, what would the decision have been for the hypothesis test?

to reject the null hypothesis

a researcher reports that stress levels around nurses are higher compared to stress levels in the general population. t(20)= 2.086, p= .05 (d=.12) was this a one tailed or a two tailed test?

two tailed bc the p value is equal to .05

compared to the independent sample t test, the related samples design decreased....

standard error

which of the following is a characteristic of confidence intervals? a) the less certain an estimate, the more precise the estimate b)the more certain an estimate, the less precise the estimate c) both a and b

c

the related samples design can....

be more practical

which of the following words best describes certainty?

confidence

a key difference between t statsitics and a z statistic is that the standard error is ____ to compute a t statistic

estimated

which type of error is used to compute the confidence interval for a one sample selected from a population with an unknown variance?

estimated standard error

all other things being equal, reducing the level of significance form .05 to .01 will ____ the value of the test statistic for a related samples t test?

have no effect

the smaller the level of confidence, the ____ precise the estimate

more

what are the degrees of freedom for the related samples t test?

n-1

a researcher increases his level of confidence from 90% to 95%. what will happen to his precision of his estimate?

the estimate will be less precise

there are 32 participants who are assigned to participate in a study with one group. what are the degrees of freed for this test?

31

computing a one sample t test is appropriate when a) participants are assigned to one group only b) the population variance is unknown c) participants are observed one time d) all of the above

d

is a one sample t test reported differently for a one tailed and a two tailed test?

no the same values are reported

a researcher measures deviant behavior in a sample of 12 children from abusive homes (sample a). another researcher measures the same behavior in a sample of 18 children from abusive homes (sample b). which sample is associated with a larger degrees of freedom?

sample b

the denominator of the test statistics for a related samples t test a) compares mean differences observed to the mean differences sated in a null hypothesis b) is the sum of difference scores for each participant c) provides an estimate of the error associated with the original scores d) provides an estimate of the error associated with the difference scores

d

which of the following is an assumption for computing the related samples t test? a) the population being sampled from is normally distributed b) the population variance of difference scores is unknown c) samples are related or matched between group, but not within groups d) all of the above

d

a researcher reports that college students consume an average of 3.6 alcoholic drinks per week. what is the interval estimate in this example?

the interval estimate is not given

which type of error is used to compute the confidence interval for two related samples selected from at least one population with an unknown variance?

estimated standard error for the difference scores

a researcher reports a significant effect in some population. if he computes both an eta-squared and an omega squared effect size estimate, then which estimate will be the largest?

eta-squared

a professor teaches a certain section of material using a lot of examples with sports and cars. he is concerned that this may have biased his instruction to favor male students, to test this he measures exam grades among women (n=10) and men (n=10), the mean score in the male group was 84± 4 (M± SD). in the female group is was 78 ± 8 (M ±SD). if the null hypothesis is that there is no difference in exam scores, then test the null hypothesis at a .05 los.

exam scores were significantly higher in the male group, t(18)= 2.12, p<.05

if the value stated by the null hypothesis is ____ the confidence interval, then the decision would have likely been to retain the null hypothesis

inside

a researcher reports a significant effect with t(14) 0= 3.24. compute the eta-squared for this result.

n2= .43 large effect size

to increased the value of estimated Cohen's D, a researcher increases the sample size. will the change the value of d?

no, the sample size is not used to compute the effect size

a researcher reports a significant mean difference in a given population, if she computes both eta-square and omega-square to measure the effect size, then which estimate will be the most conservative?

omega-squared

a researcher sampled 16 couples and measured the mean difference in their martial satisfaction. each couple was paired and the differences in their ratings were taken. if the mean difference in their satisfaction ratings was 1.8±2.0 (M±SD), and what is the decision at .05?

satisfaction ratings differ significantly, t(15)=3.60

all other things being equal, as the sample size increases, what happens to the critical value for the related sample t test (or for any t test)?

the critical value decreases

which of the following best describes the goal of estimation?

to narrow in on the true population mean by defining limits within which it is likely to be contained

a professor compares final exam scores in his psychology class to final exam scores to another professors class, assuming that the population variance in unknown, what type of test is best?

two independent t test

the confidence interval for one sample selected from a population with a known variance is computed using a critical value for which type of test?

z test

a type of related samples design in which participants are observed more than once is called a...

repeated measures design

two researchers compute a two independent sample t test. for both test, the standard error is the same, but the mean difference between the groups is larger for researcher a. which test is more likely to result in the decision to reject the null hypothesis?

researcher A

a researcher measures mean health scores of children at a local school and compares these scores to the mean health score of a known in the general population. assuming that the population variance is unknown, what type of test is best?

one sample t test

the______ is an inferential statistics 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 statistics

a researcher reduces her level of confidence from 99% to 90%, what will happen to the precision of her estimate?

the estimate will be more precise

a local elementary school determined that the average number of volunteers for their "step into spring" fundraiser has been 14 people on average after taking additional measures to recruit volunteers this year, they got 28 people. test whether the addiction measures increased the number of volunteers at a .05 level of significance

there is not enough info to answer this question

the test statistics for a related samples t test makes test concerning a single sample of...

difference scores

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

+/-2.086

which measure of effect size is most commonly reported with a t test?

Cohen's D

which type of error is used to compute the confidence interval for two independent samples selected from at least one population with an unknown variance?

estimated standard error for the difference

a researcher asks a sample of brothers and sisters to rate how positive their family environment was during their childhood. in this study, the differences in rating between each bother and sister were compared. what type of design is described here

a match samples design

each other following is needed to compute Cohen's D except a) the mean difference b) the standard error c) the standard deviation of difference scores

b

each of the following is an advantage for using the related samples design, except a) it can be more partial b) it minimizes standard error c) it increases the power of a research design d) it increases the variability measured in a study

c

computing a two independent sample t test is appropriate when a) different participants are assigned to each group b) the population variance is unknown c) participants are observed one time d) all of the above

d

the confidence interval for samples selected from a population with an unknown variance is computed using critical values from the t table. this is true for which of the following types of samples? a) one sample b) two independent sample c) related sampled d) all of the above

d

which of the following is an assumption for the two independent t test but not the one sample t test? a) normality b) random sampling c) independence d) equal variances

d

a researcher conducts a study and concludes that a new behavioral health treatment program significantly reduces ones risk for disease compared with risks level of the general populations ( d= -.64) interpret the size of this effect

risk levels in the population shifted .64 standard deviations below the mean

the estimated standard error in the t statistics uses _____ to estimate the _____ when the population variance in unknown

sample variance; population variance

a researcher has participants rate the likability of a sexually promiscuous person describes in a vignette as being a male (n=20) or female (n=12). the mean likability ratings in each group were 4. if the null hypothesis is that the is no significant difference in likability rating, then do likability ratings differ at a .05 level of significance?

no, this result was not significant t(31)=0

the t distribution is similar to the z distribution except a) it is associated with greater variability b) is it characterized by thicker tails compared with the z distribution c) is it associated with scores being more likely in the tails of the distribution d) all of the above

d

state the critical value for a test using a .05 in the lower tail only: t(24)

-1.711

a researcher reports with 90% confidence that 31% to 37% of americans believe in ghosts. what is the point estimate interval?

34%

each of the following is an estimate of error for a t test except a) standard error b) estimated standard error c) estimated stranded error for the difference d) estimated standard error for the difference scores

a

to compute a one sample t test, a researcher has to know many values. which of the following is NOT a value that the researchers much know to compute this test. a) the estimated standard error must be known b) the population variance must be known c) the sample size must be known d) the sample mean and sample variance must be known

b

to compute a two independent t test a researcher has to know many rules. which of the following is NOT a value that the researcher must know? a)the pooled sample variance b) the pooled population variance c) the sample size for both samples d) the sample mean for both samples

b

it is the most appropriate to report effect size with a significant result. why is it genially inapporpriate to report an effect size with insignificant results? a) bc insignificant results will always have an effect size equal to 0 b) because insignificant results indicate that an effect size is also insignificant c) bc it makes little sense to report the size of an effect that you just concluded doesnt exists

c

one difference between a repeated measures design and a match samples design is that a) only one design is a type of related sample design b) only one design increased the power to observe an effect c) only one design involves observing the same participants in each group d) only one design eliminated between-persons variability

c

which of the following is the numerator of the test statistic for the related samples t test? a) the same of the difference score for each participants b) the value of the test statistic plus the degrees of freedom c) the mean difference observed minus the mean difference stated in the null hypothesis d) estimated standard error for the difference scores

c

a point estimate is typically reported with an interval estimate. why? a) using only a point estimate is associated with low certainty b)the interval estimate gives researchers a higher level of confidence c)the interval estimate adds certainty to the estimate of the population mean d) all of the above

d

which of the following summarizes a t test that was significant and associated with a large effect size? a) t(22)= 3.02, p< .05, d=.36 b) t(30)=1.03, p> .05, d=.20 c) t(60)=1.76, p> .05, d=.45 d) t(12)=2.95, p< .05, d=.82

d

a researcher reports that the mean time it takes to complete an experimental task is 1.4 ± 8.0 (M ± SD) seconds. if the null hypothesis was that the mean equals 1, then what is the effect size for this test using estimated Cohen's D?

d= .05; small effect

a researcher reports that the mean rating of liking for some food are .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=.33 medium size (mean/SD)

a researcher reports that the mean difference is response time to an auditory versus a visual cue is .83 seconds, with a pooled sample variance equal to 2.45. what is the effect size for this test using estimated Cohen's d?

d=.53 medium effect size

a researcher reports that the mean difference in the body weight of rats following a pharmacological versus control treatment is 14 grams, with a pooled sample variance equal to 256, which is the effect size for this test using esteemed Cohen's d?

d=.88 large effect size

a statistical prodecure in which a sample statistic is used to estimate the value of an unknown population parameter is called....

estimation

the larger the level of confidence, the ________ precise the interval estimate

less

a researcher records the number of distracters that preschool aged children ignored while watch tv. assuming that the population variance is unknown, what type of t test is best for this study?

one sample t test

you read about a study testing whether night shift workers sleep the recommended 8 hours per day. assuming that the population variance of sleep in unknown, what type of test is best?

one sample t test

eta-squared is computed_____ for the one sample, and the two sample independent sample t tests.

similarly

which type of error is used to compute the CI for one sample selected from a population with a known variance ?

standard error

a researcher conducts two test. one test is a one tailed test with a smaller sample size and the second test is a one tailed test with a larger sample size. what do you know about the critical values for each test?

test 2 is associated with a smaller critical value

as a requirement for a t test, researchers compute any type of test with samples selected from populations in which...

the population variance in unknown

a research conducts a study measuring brain activity of rats placed on either a continuous or intermittent reward schedule. assuming that the population variance is unknown, what type of t test is best for this study?

two independent t test

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), then what us the critical value for this test?

± 2.110

for the related samples t test, assuming that all other values remain constant, then as sample size increases a) the values of the test statistics increases b) the power to detect an effect increases c)the estimate for standard error decreased d) all of the above

d

which of the following explains why point estimation can be a useful procedure to estimate a population mean? a) it defines the range of scores within which the population mean is likely to be contained b)the sample mean is equal to the population mean on average c)the sample mean is an unbiased estimator of the population mean d) both b and c

d

a researcher selects a sample of 16 women and asks them to rate how important a sense of humor is in someone that they want a long term relationship with. she records scores averaging 1.6 ± .8 (M ± SD) on a rating scale from -3 to 3. assuming that an average score of 0 is the null hypothesis, test whether or not women find this trait important at a .05 level of significance.

women found this trait to be important, and the result was significant, t(15)=8.00, p <.05

state the critical values for the values two tailed t test at a .05 level of significance: t(∞)

+/-1.645 and +/-1.96

a researcher reports that the effectiveness of a new marketing campaign significantly increased sale compared with the pervious campaign strategy. t(49)= 2.562, p< .05. use eta squared to interpret the effect size for this result

12% of the variability in marketing effectiveness can be accounted for by the new marketing strategy

which of the following is an advantage for selecting a related samples compared to selecting independent samples in behavioral research? a) selecting related samples can be more practical b) selecting related samples minimizes standard error c) selected related samples increases power d) all of the above

d

which of the following is an assumption for computing any type of independent sample t test? a) data in the population are normally distributed b) data was obtained using random sampling c)the probabilities of each measured outcome in a study are independent d) all of the above

d

if the value stated by the null hypothesis is ______ the confidence interval, then the decision would have likely been to reject the null hypothesis

outside

a researcher records the crying time of infants given an oral administration of sucrose (n =12) or tap water (n =16) prior to each heel prick, the mean crying time for the sucrose was 3.3 ± 2.4 (M ± SD). the in tap water group it was 7.3 ± 1.6 (M ±SD). if the null hypothesis is that there is no difference in crying time, then what is the decision for this test?

reject, crying time was significantly reduced amount infants given the sucrose solution prior to the heel prick

all other things being equal, as the degrees of freedom increases, what happens to the critical value for any t test?

the critical value decreases

Using APA format, which value is typically given in parentheses when reporting results for a t test?

the degrees of freedom

two researchers analyze the same data set. researcher a uses a two independent sample t test and decides to retain the null hypothesis, researcher b uses a related samples t test and decides to reject the hypothesis. which of the following is an explanation for the disparity in the decisions made.

the related samples t test had a greater power to detect the effect

when reporting data in a results section it is ____ necessary to identify the type of t test computed.

not

a researcher records differences in ratings of emotions among participants watching either a drama or a romance film. assuming that the population variance is unknown , what type of test is best for this?

two independent t test

the related samples design can___ the power to detect an effect by making the standard error _____

increase; smaller

if the null hypothesis is inside the CI, then the decision was likely to _____ using hypothesis testing

retain the null hypothesis

a researcher conditioned rats to fear a tone that was sounded just prior to a brief shock, to measure fear following this condition, she records the number of lever presses by each rat in the presence and in the absence of the tone. it was hypothesized that reduced lever pressing in the presence of the tone was evidence for a conditioned fear response in rats. if the researcher tested this hypothesis at a .05 level of significance (two tailed) then what is her decision if she computes t= -2.842 in a sample of 8 rats.

reject the null hypothesis; there is evidence for a conditioned fear response

a researcher conducts a study in which different participants are independently observed within groups, and the sample participants are observed between groups. if there are only two groups, then what type of t test is appropriate for this study?

related sample t test

a researcher conducts a study in which the same participants are observed across levels of the independent variable. if there are only two levels of the independent variable, then what type of t test is appropriate for this study?

related samples t test

two researchers (a and b) compute a two independent sample t test. for both test the mean difference between the groups is 10, but the standard error is smaller for researcher A. which test is more likely to result in a decision to reject the null hypothesis?

researcher A

two researchers compute a one sample t test, for both tests, the standard error is the same, but the mean difference between the sample and the value stated in the null hypothesis is smaller for Researcher A. which test is more likely to result in a decision to reject the null hypothesis?

researcher B

a researcher test how well participants know their spouse while under hypnosis, and again without hypnosis. it was hypothesized that the participants responses would be more accurate 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 of scores was 2.52, then what was the decision at a .05 level of significance?

retain the null hypothesis; responses were more accurate under hypnosis

a researcher conducts two t tests. test one is a two tailed test with a smaller sample size at a .05 los. test two is a two tailed test with a larger sample size at a .05 los. what do you know about the degrees of freedom for each test?

test 2 is associated with a larger degrees of freedom

to compute a related samples t test, a researcher has to know many values. which of the following is NOT a value that the researcher must know to compute this test?

the population variance of difference scores

how does the test statistics for a t test using the repeated measures versus the matched samples design?

the test statistics for the repeated measures and the matched sample designs do not differ; the test statistic is computed the same