D&A exam 2
A researcher uses a within-subjects design to observe 10 participants in each of the two groups. How many total participants were observed?
10
A group of 20 participants is observed two times. The related-samples t test for this study would have a degree(s) of freedom equal to:
19
What is the obtained t statistic?
2.48
A researcher conducts a two-independent-sample t test with a sample of 24 participants, where 12 participants are observed in each group. What are the degrees of freedom for this test?
23
. A researcher reports a two-independent sample t test statistic of t = 2.53 with df = 24. How many individuals participated in the researcher's experiment?
26
What is the mean of the nonhumorous sentences?
3.00
A researcher selects a sample of 32 participants who are assigned to participate in a study with two groups. What are the degrees of freedom for this test?
30
What is the degree of freedom?
30
What is the mean of the humorous sentences?
4.25
A research design in which different participants are observed one time in each group of a research study is called:
Between-subjects design
An example of matched-pairs by experimental manipulation would be if we matched one female with one male participant.
False
The estimated Cohen's d formula for the related samples t test is the mean difference between two the samples in the numerator and the standard deviation of the difference scores in the denominator.
False
A social psychologist records the number of outbursts among students at two schools. The data was reported as follows: t(38) = -4.19, p < .05, d = 0.25. Was the effect size small, medium, or large?
Medium
A researchers reports with 95% confidence t and hat the population parameter of americans who believe in ghosts is between 10.8 and 21.0. Based on the null hypothesis of the two-independent samples t test, would the researcher reject or retain the null?
Reject
To report the results of a t test, which of the following is not reported
The critical values
As a requirements for the t test, researchers compute any type of t test with samples selected from populations in which
The population variance/standard deviation is unknown
What is the alternative?
There will be no difference in amount of times participants left their house before or after relaxation training.
What is the null?
There will be no difference in amount of times participants left their house before or after relaxation training.
The critical values are reported with the test statistic of a paired-samples and a two-independent sample t test using APA format.
True
The two-independent samples t test can only be computed when
different participants are observed one time in each group
Is there no, a small, medium, or large effect size?
large
A researcher compares differences in personality traits among pairs of identical twins. What type of research design did the researcher use?
matched-pairs design
A researcher records the time it takes (in seconds) for participants to respond (by pressing a key) to a familiar versus an unfamiliar word flashed onto a computer screen. In this study, the difference in response time for each participant is compared. The type of design described here is called a
matched-pairs, experimental, design
A researcher compares differences in personality traits among pairs of identical twins. what type of research design did the researcher use
matched-pairs, natural occurrence design
A developmental psychologist would like to examine the difference in verbal skills for 6-year old girls compared with 6-year old boys. A sample of n = 5 girls and n = 5 boys is obtained, and each child is given a standardized verbal abilities test. What statistical test should be used to interpret the data?
paired samples t test
A researcher hypothesizes that children will eat more of foods wrapped in familiar packaging than the same foods wrapped in plain packaging. To test this hypothesis, she records the number of bites that all 24 children take of a food given to them wrapped in fast-food packaging versus plain packaging. What statistical test should she use to interpret the data?
paired samples t test
In a study on the likability of comedians, 10 participants observed one of two comedians (5 observed one who was humorous and the other 5 observed another comedian who was not humorous) and rated how likable these comedians were on a 7-point scale from 1 (not likable at all) to 7 (very likable). Which statistical test should the researcher use to interpret the data?
paired samples t test
Published reports indicate that a brain region called the nucleus accumbens (NAC) is involved in interval timing, which is the perception of time in the seconds-to-minutes range. To test this, researchers investigated whether removing the NAC interferes with rats' ability to time the presentation of a liquid reward. Using a conditioning procedure, the researchers had rats press a lever for a reward that was delivered after 16 seconds. The time that eight rats responded the most (peak responding) was recorded before and after surgery to remove the NAC. Which statistical test would the researcher need to conduct in order to interpret the data?
paired samples t test
A researcher compares differences in mean health scores between two different groups students at a local high school. Assuming that the population variance is unknown, what type of t test is appropriate for this study?
paired-sample t test
A statistical procedure used to test hypotheses concerning the difference between two population means, where the variance in one or both populations is unknown, is called the:
paired-sample t test
A researcher selects one groups of participating and observes them before and after a treatment meant to improve mood. what type of sampling design is described in this example
pre- post design
A social psychologist records the number of outbursts among students at two schools. The data was reported as follows: t(38) = -4.19, p < .05, d = 0.25. Was the decision to reject or retain the null hypothesis?
reject
Do you reject of obtain the null?
reject
Do you reject or retain the null?
reject
A researcher observes the same group of participants in the morning and again at night. What type of research design did the researcher use?
repeated-measures design
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, within-subjects design
The lower and upper 95% confidence intervals with p = .05 are 1.52, 14.48. Would we reject or retain the null hypothesis?
retain
You run SPSS and get a Sig. (two-tailed) value of .201. The decision is to
retain the null hypothesis
The correct results for this study are?
t(6)= -3.36, p<.05 d= -1.27, CI= - 13.83, -2.18
The assumptions for computing the related/paired sample t -test include
the data in the population of differences scores are normally distributed
which of the following is the numerator of the test statistic for the related/paired samples t- test
the mean difference observed minus the mean difference stated in a null hypothes
Which of the following is the numerator of the test statistic for the related samples t test?
the mean difference observed minus the mean difference stated in a null hypothesis
Which of the following is reported only for the related-samples t test and not for the independent-sample t test?
the test statistic
the degrees of freedom for the related/paired samples t test is the number of difference scores minus one
true
. A researcher conducts a study in which the same participants are observed across each level of the independent variable. If there are two levels of the independent variable, then what type of t test is appropriate for this study?
two-independent sample t test
. A researcher would like to examine the effect of hypnosis on cigarette smoking. The researcher selects a sample of smokers (n = 4) for the study, and records the number of cigarettes smoked on the day prior to treatment. The participants are then hypnotized and given the posthypnotic suggestion that each time they light a cigarette they will experience a horrible taste and feel nauseous. The researcher then records how many cigarettes they smoked after treatment. What statistical test should the researcher use to interpret the data?
two-independent sample t test
A developmental psychologist would like to examine the difference in verbal skills for 6-year old girls compared with 6-year old boys. A sample of n = 5 girls and n = 5 boys is obtained, and each child is given a standardized verbal abilities test. What statistical test should be used to interpret the data
two-independent sample t test
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?
two-independent sample t test
A statistical procedure to test hypotheses concerning two related samples selected from populations in which the variance in one or both populations is unknown is called a
two-independent sample t test
An instructor believes that students do not retain as much information from a lecture on a Friday compared to a lecture on a Monday. To test this belief, the instructor teaches a small sample of college students pre-selected material from a single topic on statistics on a Friday and on a Monday. All students receive a test on the material on Friday and on Monday. What statistical test should the instructor use to interpret the data?
two-independent sample t test
Do you need to calculate Cohens D?
yes