osu 2220 final
If you calculate the standard deviation of a distribution of scores and obtain a value of 0, which of the following statements is necessarily true?
There is no variability in the distribution—that is, all of the scores are the same.
If we were interested in studying the effect of drug abuse on employment we would probably use a ___________ study because of ethical issues involved in employing random assignment.
correlational
Your instructor decides to test the effectiveness of two different lecture techniques—multimedia vs. discussion—for her two sections of statistics. In one section she uses the multimedia technique during the first half of the semester and discussion for the second half; the opposite order is used for the second section. What is the name of the technique your instructor used to avoid confounding due to order effects?
counterbalancing
The larger the effect size the:
less two distributions overlap.
Scatterplots visually depict the type of relation between two variables, such as a ________ relation where the data falls along a straight line and a(n) ________ relation, where the data follows a curved or broken pattern.
linear; nonlinear
If a student gets 98 percent on her first statistics exam, regression to the mean would predict that this student would get a (blank) score on her second statistics exam
lower
Meta-analytic studies typically including unpublished research with null findings. Thus, the effect size of meta-analytic studies is often
lower than those calculated in individual studies
In structural equation modeling, the variables that are measured are referred to as _______ variables while the ones that are of interest but not directly measured are referred to as ________ variables.
manifest; latent
Outliers have the greatest effect on the:
mean
After grading all of her philosophy exams, Sylvia realizes that the distribution of scores is positively skewed. Which measure of central tendency would be most appropriate for Sylvia to use in this example?
median
A statement that there is no difference between populations is a:
null hypothesis
Statistical power can be defined as the probability:
of correctly rejecting the null hypothesis.
There are three different types of Olympic medals: gold, silver, and bronze. What kind of variable describes the different types of Olympic medals?
ordinal
In a within-groups design where each participant is measured twice, the appropriate hypothesis test is a(n):
paired-samples t test.
When Tyrone says, "I think there's only a 30% chance I'll get to class on time today," he is using ________ probability.
personal
Regression is to ________ as correlation is to ________.
prediction; relation
The branch of social science that specializes in the development of tests and measures is called:
psychometrics
The branch of statistics used in the development of tests and measures is called
psychometrics
Which of the following reports of statistical results is in appropriate APA format?
r(69) = 0.236, p = 0.048
The type of sampling that leads to a representative sample is _______ sampling.
random sampling
The total number of women in a country is an example of which kind of variable?
ratio
The tendency of scores that are particularly high or low to drift toward the mean over time is called:
regression to the mean
Partial correlation investigates the correlation between two variables after statistically ________ the effect of a third variable.
removing
The range of raw scores contained in an 85% confidence interval will be ______ the range of raw scores contained in a 95% confidence interval.
smaller than
The ___________ is the most common measure of variability because it uses every score in a distribution and is easy to interpret.
standard deviation
The standard deviation of the sampling distribution of means is called the:
standard error
Which of the following will impact the width of the confidence interval for an independent-samples t test?
standard error
The measure of variability used when calculating a confidence interval based on the z statistic is:
standard error.
The process of converting individual raw scores in a distribution to a set of scores for which we know the percentiles is:
standardization
Probability values are:
stated as proportions
Identify the shape of the distribution of the following scores: 6, 7, 7, 12, 17, 17, and 18.
symmetrical
The results of an independent-samples t test designed to compare differences in verbal aggression revealed no statistically significant gender differences for 15 men and 15 women (t = 1.65). Which of the following represents correct and proper APA reporting of these results?
t(28) = 1.65, p > 0.05
Tara wanted to assess the reliability of her measure of happiness so she had a group of introductory psychology students complete the measure of happiness two times and then compared the scores-calculating a correlation coefficient. What method did Tara use to assess reliability?
test-retest
Professor Taylor recently administered a psychology exam and was surprised to see that the distribution of scores was positively skewed. For this example, a positively skewed distribution indicates ________.
that most students did poorly on the exam but a few did very well
A calculated effect size of -0.75 for a paired-samples t test would tell us:
that the sample means were 0.75 standard deviation units apart.
When calculating a confidence interval for an independent-samples t test, what value should be at the center of the interval? Correct!
the difference between sample means
In a study of the effects of humor on memory, Schmidt (1994) assigned participants to read either humorous sentences or non-humorous sentences and then later tested participants' memory for the sentences. The control group in this experiment was:
the group of participants assigned to read non-humorous sentences.
A researcher observed that children playing violent video games were more aggressive than those that did not play violent video games. For this study, what is the dependent variable?
the level of aggression displayed by the children
1 / 1 pts Which of the following provides a measure of practical importance?
the measure of effect size d
A z statistic indicates:
the number of standard errors a sample mean is from the population mean
Two events are said to be independent events when:
the probability of one event is not influenced by the occurrence of the other event.
One way to think of standard error of estimate is as:
the standard deviation of the points around the regression line.
Professor Gomez designs a study to assess the role of imagination inflation on the development of false memories. Research participants are given a number of simple tasks (e.g., tapping a pencil or bouncing a ball) that they will either perform or simply imagine performing. Later their memory of whether or not they performed the task will be assessed. If graphing the results of this study, where should we place the memory scores?
vertical (y) axis
The advantage of standardization is that:
we know the percentiles to which standard scores correspond
Levene's test is significant, F(65) = 9.878, p = 0.003, which means that...
we should assume that the variances are unequal.
Data from the 1993 World Almanac and Book of Facts were used to predict the life expectancy for men in a country from the life expectancy of women in that country. The resulting regression equation was ypredicted = 9.32 + 0.79x. This regression equation implies that:
when a woman's life expectancy increases by 1 year, a man's life expectancy increases by 0.79 of a year.
Hypothesis testing tells us:
which differences are statistically significant.
Which of the following designs would be most susceptible to order effects?
within-groups, before and after design
Imagine that you randomly select a sample of 30 newborn infants and find that their mean weight is 8.1 pounds. What would you calculate to compare the mean of this sample to the mean of the population?
z statistics
When creating a 95% confidence interval for a sample mean used in a z test, you look up the:
z value cutoffs for the middle 95% of the distribution.
In a study designed to predict blood cholesterol levels from the amount of daily saturated fat in grams (x1) and the number of hours of daily exercise (x2) we determine that the slope of x1 is 4, the slope of x2 is -6 and the y-intercept is 170. Which of the following is the regression equation for this data?
ŷ = 170 + 4x1 - 6x2
To what percentile does a z score of -1.0 roughly correspond? Enter only numbers (e.g., 2nd = 2).
16
In a dependent-samples t test, the null hypothesis posits that the mean of the comparison distribution is:
0
When calculating variance, the mean of the deviations is always equal to:
0
A researcher wondered if his new relaxation training method would result in better than average results in helping people to stop smoking. He recorded the average number of cigarettes smoked for 40 of his patients immediately before undergoing the relaxation training program and again six months after completing the program. The degrees of freedom for this test are: Correct!
39
You are conducting an independent-samples t test with 22 participants in each of two groups. What are the degrees of freedom for this problem?
42
If the student newspaper reported "51% of students support the move to 4-day-a-week classes with a margin of error of 4%," which of the following would represent the interval estimate?
47% to 55%
In 2006, a sample of 400 students, whose family income was between $70,000 and $80,000, had a verbal SAT score of 513. The point estimate of the mean score for this group is:
513
A Pearson correlation coefficient is calculated for 78 individuals. What value of df should be used to determine statistical significance in hypothesis testing?
76
On one of his GRE subtests, your cousin got a z score of 1. What is his percentile of score? Enter only the number (e.g., 50th percentile = 50).
84
As sample size increases, the distribution of scores in the sample:
approaches the shape of the distribution of scores in the population.
In general how does the pooled variance estimate impact the results of an independent-samples t test?
A smaller pooled variance estimate makes it more likely that we will reject the null hypothesis.
On April 16, 2007, the BBC news reported the results of a study done by Dr. David Lewis of the Mind Lab in the United Kingdom. Dr. Lewis found that eating dark chocolate had longer-lasting excitatory effects on the body than did kissing your romantic partner. Based on his statement, it is evident that:
Dr. Lewis rejected the null hypothesis.
One assumption for using hypothesis testing for Pearson correlation is that one variable should vary equally at each level of the other variable. What is the easiest way to determine if this assumption has been met?
Draw a scatterplot to see if the range of values is equal across all values of the other variables.
Other factors remaining constant, how does SM affect the width of a confidence interval?
If SM is larger then the confidence interval will be wider.
Other factors remaining constant, how does sdifference affect the width of a confidence interval?
If it is large then the confidence interval will be wider.
How is the formula for Cohen's d different from the formula for the independent-samples t test?
In the denominator, we use pooled standard deviation rather than standard error.
why are samples more commonly studied than populations?
It is usually impossible to study a whole population
Imagine that you randomly select a sample of 30 newborn infants and find that their mean weight is 8.1 pounds. Would a sample mean as large as 8.1 be more or less likely if N = 10? Why?
It would be more likely because the sampling distribution of the mean would be wider if the sample were smaller, so sample means would be more likely to be farther from the population mean.
Mehl (2007) published in the journal Science the results of an extensive study of 396 men and women, comparing the number of words uttered per day by each sex. Assuming a two-tailed test, which of the following would be the null hypothesis?
Men and women do not differ in the number of words uttered.
Suppose we are interested in examining the social aspects of eating behavior. Twenty participants are placed in a room with various types of snack foods and are told to eat whatever they like while they are waiting for the researcher. Ten of the participants wait alone while the other 10 wait with two other people. The research hypothesis in this experiment is that when participants wait with others they will eat less food than when they wait alone. If we fail to find a difference between the two groups which of the following might be true?
Our small sample size may have resulted in low statistical power.
What is one important reason for looking at visual descriptions of data such as a frequency histogram?
Patterns revealed in the data may lead to more specific research questions.
________ is a weighted average of the two estimates of variance that are calculated when conducting an independent-samples t test.
Pooled variance
The distribution against which the Pearson correlation is compared is the (blank) distribution
R
(blank) regression enables one to predict an individual`s score on the dependent variable from his or her score on a single independent variable
Simple linear
_________ multiple regression involves allowing the computer software to determine the order in which independent variables are included in the equation.
Stepwise
________ is a technique that quantifies how well sample data "fit" a theoretical model that hypothesizes a set of relations among multiple variables.
Structural Equation Modeling
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.
How is the formula for Cohen's d for a paired-samples t test different from the d formula for the single-sample t test?
The mean and standard deviation are for difference scores rather than individual scores.
The regression line is the line that:
The regression line is the line that:
A recent study investigated the possible effects of hair loss prevention drugs (e.g., Propecia) on men's sexual interest (libido). Suppose the researchers measured libido both before and after use of the drugs and reported these findings from a paired-samples t test: t (48) = 5.45, p < .01. What could we conclude about the results of this study?
The researchers found a significant difference in libido before and after taking the drugs.
What does the slope tell us about the correlation coefficient?
The sign of the slope (positive or negative) tells us the direction of the correlation
How does the sampling distribution of means for a sample with N = 5 differ from that of a sample with N = 100?
There is more variance in the sample distribution with N =5 than with N = 100
In a study of the effects of humor on memory, Schmidt (1994) assigned participants to read either humorous sentences or non-humorous sentences and then later tested participants' memory for the sentences. Identify the null hypothesis this study.
There is no difference in the memory for humorous and non-humorous sentences
A study by Goldstein et al. (1997) examined the effect of playing video games on the reaction time of elderly individuals. Volunteers in the experimental group played the puzzle game Tetris five hours a week for five weeks. Control group participants did not play the game. At the end of the study Goldstein et al. rejected the null hypothesis. What does this mean?
There was a difference in reaction time between the two groups and this difference was caused by whether or not the participants played the video game.
A study by Bettmann (2007) published in the Journal of the American Psychoanalytic Association assessed whether the attachment relationships between adolescents and their parents change as a result of a residential wilderness treatment experience for the adolescents. Participants completed the Adolescent Attachment Questionnaire at the start and at the end of the wilderness program. Which of the following would be the null hypothesis for this study?
There will be no difference in attachment relationships after the wilderness experience.
Which of the following reports of statistical results is in appropriate APA format?
Which of the following reports of statistical results is in appropriate APA format?
On April 16, 2007, the BBC news reported the results of a study done by Dr. David Lewis of the Mind Lab in the United Kingdom. Dr. Lewis found that eating dark chocolate had longer lasting excitatory effects on the body than did kissing your romantic partner. This is the first study to show such large effects of chocolate. If no subsequent studies can replicate this finding, it implies that the researchers made what kind of error?
a Type I error
A positively skewed distribution is more likely to occur whenever we have:
a floor effect
What falls within the 95% confidence interval?
a set of values that will include the population mean 95% of the time when repeatedly sampling from a population
In hypothesis testing we:
always testing the null hypothesis
As standard error of estimate gets smaller, our predictions:
become more accurate.
As sample size increases, the shape of the sampling distribution of the mean:
becomes narrower
Roman wanted to assess the internal consistency of his measure of happiness so he measured reliability estimates by comparing items within his test. He reported a reliability estimate of 0.75. What measure of reliability is Roman using?
coefficient alpha
Performing inferential statistics often involves:
comparing the observed mean to a distribution of means.
One reason for doing correlational research is to evaluate the relationship between two variables that are related to each other, either positively or negatively. However, a correlation is vulnerable to what type of variable, which systematically covaries with the variable of interest?
confounding
If your coach reports the team's race averages to two decimal places (e.g., 15.04 seconds) this would be considered a(n) ___________ observation.
continuous
A(n) __________ is a level of the independent variable that does not receive the treatment of interest in a study.
control group
As part of their work in a research methods class, a group of psychology students devised a survey to assess the relationship between sleep and health. Each member of the class administered the survey to five of their friends, and the data were then pooled. What method of sampling was used?
convenience sampling
Correlations are often used to assess (blank) by measuring the strength of the association between scores on a new measure and an existing measure designed to assess the same construct.
convergent validity
An unstandardized measure of the linear association between two scale variables is a
covarient
One of the first steps in calculating the paired-samples t statistic is:
creating a difference score for each pair in the sample.
As sample size increases, the standard error:
decreases1
Another name for a paired-samples t test is:
dependent-samples t test.
when your professor announces the average exam score she is using
descriptive statistics
The main difference between an interval variable and a ratio variable is that an interval variable:
does not have a true zero point
1995 data from over 1,000 colleges published in U.S. News & World Report were used to predict the percent of alumni who donate to a college from the average SAT score of students attending that college. The resulting regression equation was ypredicted = -29.29 + 0.05x. This regression indicates that:
for every 1 point increase in SAT scores, a college can expect to get 0.05% more of its alumni donating
The extent to which research findings from one sample or context can be applied to other samples or contexts is called:
generalizability
Suppose students are randomly assigned to either get positive feedback or not get positive feedback for their performance on daily quizzes and we measured their attitudes towards the class at the end of the semester. What is the independent variable in this study?
getting positive feedback or not getting positive feedback
Other things being equal, a larger sample size will _______ effect size.
have no effect on
Random assignment in experiments is important because it:
helps to control confounding variables
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.
In _________ multiple regression the researcher adds independent variables into the equation in an order determined by theory
hierarchical
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.
The difference between the denominator of the z test and that of the single-sample t test is that:
in the z test we divide by the actual population standard error (This answer is set as correct), but in a t test we divide by the sample standard error (This answer is set as correct).
Mehl (2007) published in the journal Science the results of an extensive study of 396 men and women, comparing the number of words uttered per day by each sex. What statistical test should Mehl use to analyze the data?
independent-samples t test
what is the primary difference between descriptive and inferential statistics?
inferential statistics allow researchers to draw conclusions about populations while descriptive statistics simply organize and summarize date
Pearson correlation coefficient can be used with:
interval or ratio data.
A measure is said to be valid if:
it measures what it is supposed to measure.
If our data is nominal we should use _________ as a measure of central tendency.
mode
A researcher wants to be able to predict first semester college grade point averages with as much accuracy as possible and so she would like to use both high school grade point averages and SAT scores as predictor variables. Which of the following techniques would be most appropriate to make this prediction?
multiple regression
The formula for the degrees of freedom for the single-sample t test is:
n-1
The formula for the degrees of freedom of a Pearson correlation coefficient is
n-2
As sample size gets larger the t distributions get:
narrower.
With very few degrees of freedom, the test statistic:
needs to be more extreme to reject the null hypothesis.
What kind of correlation would you expect to find between rainfall and sales of sunscreen?
negative
The numbers on athletes' uniforms are an example of a(n) _________ variable.
nominal
A bar graph is usually used with __________ data, while a histogram is used with _________ data.
nominal;scale
Inferential statistical analyses that are NOT based on a set of assumptions about the population are:
non-parametric tests.
Imagine that a study of memory and aging finds that younger participants correctly recall 55% of studied words, older participants correctly recall 42% of studied words, and the size of this effect is Cohen's d = 0.51. This effect size indicates that the memory performance of:
older participants is approximately half a standard deviation below that of younger participants.
A point estimate is:
one number used to estimate the population parameter.
A duplication of scientific results in a different context or with a different sample is:
replication
A negatively skewed distribution has a long tail to the ________ of the distribution, while a positive skew has a long tail to the ________ of the distribution.
right; left
College students at 50 campuses around the country were polled to how many students owned smart phones. This small representative group of students is called a:
sample
When calculating a confidence interval for a paired-samples t test, what value should be at the center?
sample mean difference
A _________ variable meets the criteria for either an interval variable or a ratio variable.
scale
________ are an efficient way to visually display the data to identify any outliers that may skew the distribution.
scatterplots
Effect sizes rely on comparison of a distribution of ________ rather than on a distribution of ________ and are therefore unaffected by sample size.
scores; means
Assuming critical values of -2.306 and +2.306 for an independent-samples t test, if we obtain a calculated t value of -2.30 we:
should reject the null hypothesis.
A newspaper article reported that the typical American family spent an average of $81 for Halloween candy and costumes last year. A sample of 16 families this year reported spending a mean of $85, with a sample standard deviation of $20. What statistical test would we use to determine whether these data suggest a significant change in holiday spending?
single-sample t test
What type of statistical test would we use to compare a sample to a population for which we know the mean but not the standard deviation?
single-sample t test
The (blank) of a correlation indicates how closely the data points cluster around the line of best fit(regression line)
slope
Pearson correlation coefficient is only appropriate when:
the variables are linearly related.
In the equation ŷ = 170 + 4x1 + 6x2, which of the following is true?
there are two slopes
What type of plot is most appropriate for visually displaying dependent variables from longitudinal studies, in which the same group of individuals is studied over time?
time series plot
The number of forest fire fatalities in California for the last ten seasons was reported as: 3, 8, 3, 7, 7, 2, 8, 6, 2, and 3. What type of distribution is this?
unimodal