Quant final exam
A medium size effect(d) for a t test for dependent means
.50
In a third world country, 100 randomly selected people were surveyed about their socioeconomic class and religion affiliation. The results and an excerpt from this fictitious study follow: Based on chi square test for independence the working class differed from the middle class in the distribution of religious identification x2. (4,N=100) = 11.73 p<.05 The percentage of the middle class respondents who were catholic?
5/34 = 14.7
Continuous variable
A continuous variable is a variable for which in theory there are an infinite number of values between two values. An examples of a continuous variable is weight
A participant in a cognitive psychology study is given 50 words to remember and later asked to read all as many of the words as possible. She recalls 17 words. A(variable) B(possible values) C(score) ?
A. The variable is the amount of words participant can recall B. The possible values are 0 through 50 C. The score is 17
The overall F statistic in an analysis of variance is called:
An omnibus F
negatively skewed unimodal distribution
Distribution where the higher the frequencies of values are located on the left side and spread out somewhat like a tail. On the right side of the distribution there is only one value that clearly has a larger frequency than any other value
In an analysis of variance what is another name for "within-groups" variance?
Error
Testing participants before and after an experimental manipulation is called?
Repeated measures
Which behavior was perceived as the least riskiest regardless of group membership
Risk of slow driving (table 3 perceptions of risky driving behavior)
The main idea of a chi test is to
Test how well the pattern observed frequencies fits some expected pattern of frequencies
Which of the following statements is true if a study measures two groups of 27 variables, and the experimenter Carrie's out a t test for independent means for each variable (that is 27 t test) using .05 significance level
The chance of at least one t test being significant is greater that 5%
The mean of distribution of mean is often
The same as population mean
S2 difference = S2M1 + S2M2; the S2M1 represents?
The variance of the distribution of means population 1
How would the results of chi square be reported x2?
X2(1)=2.88,p=.09
As the number of people in a sample gets larger, the distribution of means
becomes a better approximation of the normal curve
Making a histogram is easiest if one begins with
frequency table
The most common way for a t test for independent means to be reported in a research article is:
t(45) = 3.5, p<.05
When discussing the pattern in a contingency table the word independence means
there is no relationship between the variables
0.01 3 planned contrast
0.0033
0.10 6
0.0167
.05 2 planned contrast bonferroni??
0.025
0.10 4
0.025
What is the critical cutoff value for a two tailed single sample t test with 16 participants and p.05
2.132
If a study includes two different groups with 30 participants in each; the total degrees of freedom used to estimate variance would be
28
If a research article presented the results of an analysis of variance as, "F (2, 38) = 3.60, p < .05," then how many groups were there in the study?
3
If the variance is 9, then the standard deviation is?
3
In an analysis of variance with a between-groups variance of 30 and a within-Group variance of 25, the F ratio is
30/25=1.20
I'm which of the following situations would a t test for independent means be conducted?
A comparison of scores of participants in a memory study where one group is assigned to learn the words in alphabetical order and another group is assigned to learn the words in order of length of word
symmetrical unimodal distribution
A distribution is a pattern of frequencies for the various values of a variable collected in a study. A symmetric unimodal distribution is a distribution where there is one value with a larger frequency than any other and the pattern of frequencies on the left and right of this larger frequency are mirror images of each other
When using sample means group means, the appropriate comparison distribution is:
A distribution of means that allows an indirect comparison of each sample to its respective population
grouped frequency table
A grouped frequency table is in which the number of individuals (frequency) is given for each interval of values
Probability
A probability is equivalent to the proportion of scores that meet a certain criteria. The proportion is the faction with the number of outcomes that meet the criteria over the total number of outcomes. The probability is the decimal equivalent of the fraction
Equal interval
A ratio scale variable is an equal interval that has N absolute zero point , meaning that the value of zero in the variable indicates a complete absence of variable. An example of a ratio scale is the of number of siblings a person has.
In an analysis of variance if the within groups variance estimate is about the same as the between groups variance then
Any differences between sample means is probably due to sampling error and not treatment
As the number of people in a sample gets larger, the distribution of means
Becomes closer to being an exact normal curve
If a psychologist rating empathic responses to strangers distress on a scale of 1to 20 finds most participants have ratings of either 8 or 16, the distribution of ratings is:
Bi modal
Which statistical procedure ensures that the alpha level for any given planned contrast will not exceed.05
Bonferroni
For which of the following questions would a Chi square test for independence be the most appropriate statistic to use?
Cassandra believes people who are left handed will also kicks ball with their left foot
The proportionate reduction in error is preferred over the correlation coefficient for:
Comparing correlation coefficient across research studies
The image below is often used in journal articles to show the relationship among variables this is an image of what?
Correlation Matrix
When the relationship between variables is shown by listing the variables on both the top and left side of table is called
Correlation matrix
The final step in hypothesis testing is to:
Decide wether to reject the null hypothesis. To decide wether to reject the null, compare the actual sample Z score to the cutoff Z score. If researcher reject the null what remains is the research hypothesis which men and the findings support the research hypothesis
Which variable is statistically significant at level p<.01 (table 1)
Desire to become a parent
2nd Step of Hypothesis Testing
Determine characteristics of the comparison distribution. The overall log I've of hypothesis testing involves figuring the probability of getting a particular result if the null hypothesis is true. In this process, one wants to determine the probability of getting a sample score as extreme as the one found if the sample were from same populations with a distribution corresponding to the null hypothesis being true
3rd step of hypothesis testing
Determine cutoff sample score on the comparison distribution at which the null hypothesis should be rejected. Ideally before conducting a study researchers set a target against they will compare their results this is called cutoff sample score. Researchers often use samples scores and percentages as these cutoff sample scores
A counseling psychologist developing a technique to reduce procrastination has students time their procrastination for a week and uses a pretext measure of procrastination. Students then attend a workshop in which they are instructed to do a specific warmup exercise for studying by focusing on a pleasant activity. Students again time their procrastination for a week, and the time from this second week is posttest measure. If the psychologist want to see if there is a chance ( increase or decrease) in procrastination by students who attended his workshop, the appropriate description of "Population 2" the comparison would be?
Difference score will be 0
One way to handle a situation in which high scores go with high scores and low scores with low scores but the pattern of scores is not linear is to
Figure spearman's rho
If a psychologist summarizes data for a variable in a frequency table but finds that there are so many values for the variable that the table is too cumbersome to be useful the next step would be to make a:
Grounded frequency table
1st step of hypothesis testing
Identify the populations restate the question as a research hypothesis and a null hypothesis about the populations. Since researchers are interested in results in terms of populations it is useful to restate the research question in terms of population. The researcher hypothesis represents the research question being asked
Under what conditions can be possibly that Y causes X be ruled out when two variables X and Y are strongly correlated
If X occurs before Y
The difference between a positive and negative correlation is that
In a negative correlation, high scores go with low scores and low with high; in a posted correlation, high scores go with high scores and low with low
The best way to reduce the variance in the distribution of means when conducting a t test for independent means is to
Increase the size of samples
within-groups variance is the result of
Individual groups differences associated with unique aspects of the participants of the within groups
When conducting a t test for dependent the mean or M or u symbol
Is always equal to 0
Which of the following statements about degrees of freedom is true?
It describes the number of scores in a sample that are free to vary
What is the purpose of the post hoc test?
It identifies where the differences among the study group exists
One of the primary characteristics of an F ratio is that?
It will never be less than 0
A developmental psychologist studies the number of words that seven infants have learned at a particular age. The numbers are 11, 11, 9, 0, 4, 37, 20.
Mean= 13.143 Median= 11 SD= 11.332 The mean is the average number of words learned found by dividing the total number of word learned by the number of infants in the study. The median is the middle value in the ordered list of numbers of words learned. The SD is roughly the average number of words learned for the infants differ from the mean
The median is greater thank the mean in a distribution that is
Negatively skewed
A researcher reads a study in which the results.05 sample size very large how should this affect interpretation
Null true: There is low probability that the null hypothesis is actually true regardless of sample size Practical importance: the large sample size means that the result might or might not have practical importance Significance is based on the differences between the mean sample and know population mean, divided by the SD of distribution of means. If sample size is very large the the standard deviation of the distribution is very small. This a small difference between means when divided by a very small denominator can give an overall large result
Is the level of education for residents of a particular city different from the level of education for people living in the region
People in region, residents in particular city The level of education for residents of a particular city is different form the level of education for people in the region It's the same Two tailed because researcher is interested in the level of education for residents of a particular city differs from the level of education in the region
Do people who have experienced a flood have more or les self confidence that general population
People who have experienced a flood and general population People who have experienced a flood have more or less self confidence than general population Same amount as general population Two tails interested in wether people who have experienced flood have more or less self confidence than general population
Study is inconclusive and in reality null hypothesis is true
Pet ownership does not increase life expectancy and null suggests it does not
Suppose research hypothesis is true but in reality null hypothesis is true
Pet ownership does not increase life expectancy but the hypothesis testing suggest that it does- type 1 error
Study inconclusive but in reality research hypothesis is true
Pet ownership increase life expectancy but hypothesis testing suggest it doesn't type 2 error
research hypothesis is supported and in reality research hypothesis is true
Pet ownership increases life and hypothesis testing suggests that it does
A school psychologist surveyed 75 students both boys and girls who had been reported as bullied and asked them which bullying method they used most often physical psychological or cyber bullying the results are as follows
Physical
The primary characteristic of planned contrast is that they are
Planned before the study is conducted
Do children whose parents are professors score higher or lower than children in general exams?
Population being compared: children whose parents are professors, children in general Research hypothesis: children whose parents are professors score higher than children in general Null hypothesis: score same or lower than those in general One tailed because the researcher is only interested in wether the children whose parents are professors score higher
Suppose that a survey of visitors to a college campus was going to taken. What is the best way of selecting the people to be in survey? Why would this be the best method?
Randomly select the number of visitors from their contact information left with the school and call them to take a survey This is the best method because it is a truly random sample
An effect size of .06
Small effect size for chi square
If a t test for dependent means is reported in a research article as "t (16) = 2.67, p < .05," then
T score is 2.67
A researcher measure the resting heart rescue of a group of 15 patients before and after they take a particular drug
T test for deluxe means should be used because the two set of scores are from a single group of people
What type of test was performed to analyze these data? Table 1 means SD for level of ethnic identity other groups attitudes and perceived discrimination by age and gender for Korean
T test for independent sample means
correlation coefficient
Tell strength and direction of linear relationship
A correlation coefficient describes wether a relationship exists between two variables and the strength of the relationship. What other information does correlation coefficient provide?
The direction of the relationship
Another way to describe a negatively skewed distribution is to say that
The distribution is skewed to the left
If an experimenter conducts a test for independent means and rejects the null hypothesis the correct interpretation is that
The mean of one sample is so far from the mean of the other samples must come from populations with different means
When conducting a t test for independent means, a typical research hypothesis might be
The mean of population 1 is greater that mean of population 2
When carrying out a t test for independent means
The null hypothesis is rejected if the computed t score is more extreme than the cutoff t score
When carrying out a t test for independent means
The null hypothesis is rejected if the obtained t score is more extreme than obtained cutoff score
A developmental psychologist who wanted to know if children who started walking earlier performed better in school, divided 45 children into Early, Middle, and Late walkers at the end of the second grade computed a composite score based in teachers reports and found the following results: Early M=3.62 ( SD= 1.20); Middle M= 2.84(SD=.70); Late M=2.77(SD=.98); F(2,24) =3.466 p= 0.040 which statement best describes the results?
The omnibus F is statistically significant, however there is not enough data to determine which groups differ statistically from each other
Which of the following is MOST serious violation of an assumption for the t test for independent means?
The population are dramatically skewed in opposite directions
Analysis of Variance (ANOVA) should be conducted only when:
The population variances can be assumed equal
In a chi square for goodness of fit the null hypothesis is that
The proportion of people in each category breaks down the same for the observed and expected populations
A research testers the performance of 250 students who struggled with math, using math skills assessment test. The researcher computed a group mean of 250 students and now want to compare the results to the known standardized mean of all students who have ever taken their the test. Which test should the researcher use to analyze the data?
The researcher should use a t test for single sample means because the group's mean is being compared to a known population
When using a t table the degrees of freedom used for a t test for independent means is
The sum of degrees of freedom for the two samples
The correct description of the mean is:
The sum of the scores divided by the number of scores
If a research article reports that "The mean performance scores for the Normal Sleep, Reduced Sleep, and No Sleep groups were 18.0, 16.6 and 15.6. F(2,36)=!2.95 p<.05 the most accurate conclusion is?
The three groups differ significantly and do not all come from populations with the same mean, although it is not clear which groups differs
Which of the following would be considered a categorical variable?
The type of sport played by most 5th graders boys
A study involves measuring the number of days absent from work for 213 employees of a large company during the preceding year. As part of the results the research reports, "The numbers of days absent during the proceeding year(M=10.31; SD=6.58) was..... explain what is written in parentheses
The value 10.31 is the average number of days absent, or the number of days absent for each worker if the total number of days absent was divided evenly among the 212 workers. The values 6.58 is the square root of the average of the square of the amount of the number of days absent differs from 10.31. The value 6.58 measures how much the number of days absent are spread out.
One assumption for the t test for independent means is that
The variance of each of the parent populations is the same
Effect of chi square .33 is a medium effect size and x2 is 8.661
There is sufficient evidence that they type of success of a relationship are associated. That is the probability of a successful local relationship is different than the probability of a successful long distance relationship
For an ANOVA to be used what is the minimum numbers of groups required?
Three
In a contingency table 3by4 x2 contingency table there are
Three levels of one variable and 4 levels of the other
The normal curve is most likely described as:
Unimodal, roughly symmetrical, and bell shaped
If an intelligence test includes 12 items so that a person can answer any number of items between 0-12 correctly, each of these numbers between 0 and 13 is called a
Value
Discrete variable
Variable is a variable in which that has specific values and that cannot have values between those specific values. An example is the number of times a person has visited the dentist in the last 12 months
When conducting a t test for independent means once the variances are known for each of the distribution of means the variance can be added together to give the
Variance distribution of differences between means
If the correlation between two personalities traits is .07 the correlation is considered a
Weak linear correlation
To find the score in a t table at which the null hypothesis will be rejected an experimenter must know the significance level the degrees of freedom and
Wether it is one tailed or two tailed test
When using a t test for independent means the mean of a distribution between means is equal to:
Wrong answer difference between sample means Maybe: standard deviation of distribution of means
When comparing martial satisfaction for Time 1 and Time 2 which group has the lowest mean score?
Wrong answer is men time 2
Mean is 82 standard deviation is 11. What are the Z scores for the following raw scores? 104, 61
Z104 = 2 Z61 = -1.91
Which of the following statements is true about t-distributions
d. the larger the sample size, the more a t distribution resembles a normal curve
The two branches of statistical methods are:
descriptive and inferential
4th step of hypothesis testing
determine your sample's score on the comparison distribution this step involves carrying out the study and getting the actual results form the sample once the results are obtained the Z score is determined for the sample raw score based on population means and SD of the comparison distribution
A chi square test would be appropriate for examining the relationship between
gender (male or female) and political orientation (conservative, liberal, or other).
When testing the significance of the correlation coefficient, the null hypothesis is usually that in the population, the true correlation
is zero
The comparison distribution in a t test for dependent means is a distribution of
means of difference scores.
What symbol is used to determine correlation coefficient?
r
homogeneity of variance
the assumption that the populations, from which the sample were drawn have the same variance
