Stats
My electric bills for June, July, and August least summer were $75, $75, $150 respectively. What was the mean amount for the three bills
$100
What z-score corresponds to a score that is above the mean by 2 standard deviation?
+2
For a population with u= 40 and o=8, what is the z-score corresponding to X=34
-0.75
What is the variance for the following set of scores: 2, 2, 2, 2, 2?
0
What proportions of a normal distribution is located in the tail beyond z= 1.50?
0.0668
A vertical line drawn through a normal distribution at z=0.50 separates the distribution into 2 sections, the body and the tail. What proportion of the distribution is in the tail?
0.3085
A population has u= 50. What value o would make X= 55 an extreme value out in the tail of the distribution?
1
On avg, what value is expected for the f- ratio if the null hypothesis is true
1.00
A repeated measures study uses a total of n= 10 participants to compare two treatment conditions. How many scores are measured in this study, and how many scores are actually used to compute the sample mean and the sample variance
10 measured and 10 used
A class consists of 10 males and 30 females. If one student is randomly selected from the class, what is the probability of selecting a male
10/40
The results of a hypothesis test are reported as follows for a one-sample t-test: t(15) = 2.70 p<.05
16
A repeated measures study using sample of n=20 participants would produce a t stat with df equals ______.
19
A researcher conducts a hypothesis test using sample of n= 20 from an unknown population. What is the df value for one-sample t stat.
19
If an independent -measures design is being used to compare two treatment conditions, then how many different groups of participants would be needed nd how many scores would there be for each participant
2 groups, 1 score each
With alpha = .01, the two tailed critical region for a one- sample t-test using sample of n= 16 subjects would have boundaries of ________.
2.947
A sample with a mean of M= 40 and a variance of s^2 = 20 as an estimated standard error of 1 point. How many scores are in the sample
20
An independent- measures study uses n= 15 participants in each study group compare two treatment conditions. What is the df value for the t stat for this study?
28
If the results of an experiment using kind were summarized as t (30) = 2.817, p <.05, then you would now that the total number of participants used (N) was _________ and the null hypothesis was________.
32; rejected
A research study comparing three treatments with n= 5 in each treatment produces t1= 5, t2=10, t3=15, with ss1= 6, ss2= 9, ss3=9 and {X^2=94). For this study what is ssTOTAL?
34
For a sample with M=80, a score of X=85 corresponds to z= 2.00. What is the sample standard deviation?
4
For the population with u= 80 and o=10, what is the X value corresponding to z= -2.00?
60
A research report concludes that there are significant differences among treatments, with "F(2,24) = 8.62, p<.01. If the same number of participants was used in all of the treatment conditions, then how many individuals were in each treatment?
9
What kind of frequency distribution graph shows the frequencies as bars, with no space between adjacent bars?
A histogram
Which set of characteristics will produce the smallest value for the estimated standard error?
A large sample size and a small sample variance
A researcher lans to conduct research study comparing two treatment conditions with a total of 20 participants. Which of the following designs would produce 20 scores in each treatment
A repeated measures design
Which combination of factors will produce the largest value for the standard error
A small sample and a large standard deviation
If the null hypothesis is false and H(sub 0) is not rejected then _______
A type 2 error has occurred
What is first step to be performed when computing {(X-2)^2
Add 2 points to each score.
A hypothesis test produces a t stat of t = 2.20for a one sample test. If the researcher is using a two-tailed test with a = .05 how large does the sample need to be in order to reject the null hypothesis
At least 13
A researcher survey a sample of n=200 collenege students and asks each person to identify his or her favorite movie from the past year. If the results were presented a frequency distribution graph, what kind of graph would be appropriate?
Bar Graph
What position in the distribution corresponds to a z-score of z= -1.00
Below the mean by a distance equal to 1 standard deviation
What position in the distribution corresponds to a z-score of z= -1.00
Below the mean by a distance equal to a 1 standard deviation
In an analysis of variance, differences caused y treatment effects contribute to which of the following variances
Between treatments variance but not within treatments variance
In an analysis of variance, differences between participants contribute to which of the following variances?
Both between-treatments variance and within- treatments variance.
A sample has a mean of M=86. If one new person is added to the sample, what effect will it have on the sample mean?
Cannot be determined from the information given
In a directional one- sample t test, the rejection region is located in ______ of the sampling distribution of t.
Either the left tail, but not both tails.
Which of the following is a requirement for a random sample?
Every individual has an equal chance of being selected, the probabilities cannot change during series of selections, there must be sampling with replacement
Under what circumstances will the distribution of sample means be normal?
If the population is normal or if the sample size is greater than 30
A researcher using a two tailed hypothesis test with a = .05 to evaluate the effect of treatment if the boundaries for the critical region are t + or - 2.080, then how many individuals are in the sample ?
Impossible to determine
Compared to an independent measures design a repeated measures study more likely to find a significant effect because it reduces the contribution of variance due to _________>
Individual differences
Compared to an independent measures design, a repeated measures study is more likely to find a significant effect because it reduces the contribution of variance due to _______.
Individual differences
For the two factor between subjects ANOVA what is calculated in stage 2 of the equation?
Interaction Variance and Actor A & B variability
After measuring 2 individuals, researcher can say that Tom's score is 4 points higher than Bill's. The measurement must come from a(n) ________ scale.
Interval or Ratio
What happens to the standard error of M as sample size increases?
It decreases.
When n is small (less than 30), how does the shape of the t distribution compare to normal distribution
It is flatter and more spread out than the normal distribution
What is the "expected value of M"?
It is the mean of the distribution of sample means
Which of the following describes what a confidence interval does
It uses a sample mean to estimate the corresponding population mean
If other factors are held constant, what is the effect of increasing the sample size
It will decrease the estimated standard error and increase the likelihood of rejecting H(sub 0)
Which combo of factors is most likely to produce a significant value for an independent measure t-stat
Large Sample and small variance
In general, what factors are most likely to reject the null hypothesis for an ANOVA
Large mean differences and small variances
The _______ states that the larger the sample size (n), the more probable it is that the sample mean is close to the population mean?
Law of large numbers
On ag, what value is expected for the f-ratio if the null hypothesis is false?
Much greater than 1.0
The students in a psychology class seemed to think that the midterm exam was very exam. If they are correct, what is the most likely shape for the distribution of exam scores?
Negatively Skewed
What symbol is used to identify the standard error of M
O(sub M)
In a repeated measures experiment, each individual participates in one treatment condition and then does on to a second treatment condition. One of the major concerns in this type of study is that participation in the first treatment may influence the participats score in the second treatment. What is this problem called?
Order effects
Usingg letter grades (A, B, C, D, and E) to classify student performance on an exam is an example of measurement on a(n) ______ scale of measurement?
Ordinal
A Researcher uses an anonymous survey to investigate the TV habits of American ADOLS. The goal of the research is to determine the avg # of hours ea. day spent watching TV. Researcher is trying to determine a # that is an example of a _________.
Parameter
What term is used to describe the shape of a distribution in which the scores pile up on the left-hand side of the graph and taper off to the right?
Positively Skewed
Which of the following describes a typical distribution of f-ratios?
Positively skewed with all values greater than or equal to zero
Which of the following most accurately describes the proportions in the tails of a normal distribution
Proportions in both tails are less than .50
For a research study comparing attitude scores for males and females, participant gender is an example of what kind of variable?
Quasi-Independent Variable
A researcher is interested in the eating behavior of rats and selects a group of 25 rates to be tested in a research study. The group of 25 rats is an example of a _________.
Sample
In an analysis of variance, what is measured by the MS values
Sample Variance
The avg SAT score for an entire class of entering freshman is 530. However, if you select a sample of 20 freshman and computer their avg verbal SAT score you will probs not get exactly 530. What statistical concept is uses to explain the natural difference that exists between a sample mean and the corresponding population mean?
Sampling Error
________ is the natural discrepancy, or amount of error, between sample statistic and it's corresponding population parameter?
Sampling Error
______ is composed of scores that have been transformed to create predetermined values for the u and o.
Standardized distribution
A characteristic, usually a numerical value, which describes a sample is called a ______.
Statistic
What was the pen name of William Sealy Gosset, the creator of the t-distribution
Student
What is the final step to be performed when computing {(X-2)^2
Sum the squared values
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?
The amount of St. Johns Wort given to each participant.
Stephens, Atkins and Kingston (2009) found participants were able to tolerate more pain when they shouted their favorite swear words over and over than when they shouted neutral words. For this study, what is the dependent variable?
The amount of pain tolerance (what's being measured)
Standard deviation is probably the most commonly used value to describe and measure variability. Which of the following accurately describes the concept of Standard Deviation?
The avg distance between a score and the mean
In a two factor analysis of variance, a main effect is defined as _____?
The mean differences among the levels of one factor.
What additional information is obtained by measuring two individual on an interval scale compared to an ordinal scale
The size of the difference.
In an ANOVA,what is represented by the letter T
The sum total of the scores in a specific treatment
What is assumed by the homogeneity of variance assumption?
The two populations have equal variances
A 2x6x3 Factorial ANOVA indicates that
There are 3 independent variables, one of which has 6 levels
For an ANOVA comparing three treatment conditions, what is stated by the null hypothesis (H0)
There are no differences between any of the population means
H1
There will be an effect
H0
There will not be an effect
In an independent- measures ANOVA, individual differences contribute to the variance in the numerator and in the denominator of the f-ratio. For a repeated measure ANOVA, what happens to the individual differences in the denominator of the f-ratio?
They are measures and subtracted out in the second stage of the analysis
What is the purpose for post hoc tests?
To determine which treatments are significantly different
When comparing more than two treatment means , why should you use an analysis of variance instead of using several t- tests
Using several t tests increases risk of a Type 1 error
Under what circumstances is a score that is located 5 points above the mean a central value, relatively close to the mean?
When the population deviation is much greater than 5
Under what circumstances is a score the is located 5 points above the mean a central value , relatively close to the mean?
When the population deviation is much greater than 5
For which of the following situations would a repeated measures design have the maximum advantage over an independent measures design?
When very few subjects are available and individual differences are large
A normal distribution has a mean of u=80 with o= 20. What score separates the highest 15 % of the distribution from the rest of the scores?
X= 100.8
Scores on the SAT from a normal distribution with a mean of u= 500 with o= 100. If the state college only accepts students who score in the top 60% on the SAT, what is the minimum score needed to be accepted?
X= 475
In the first stage of a repeated measures ANOVA, total degrees of freedom is partitioned into _______________.
between treatments df and within treatments df
A type 1 error....
can occur only when the null hypothesis is true
For which of the following situation s would be a repeated measures research design be appropriate
comparing pain tolerance with and without acupuncture needles
A researcher reports t(12)= 2.86, <.05 for a repeated measures research study. How many individuals in the study
n = 13
Which of the following is the correct way to report the results of a hypothesis test and a measure of effect size using a t-stat
t(19) = 2.30, p< .05, r^2 = 0.42
Which of the following z-score values represents the location farthest from the mean
z+-2.0
For a population with a standard deviation of o=10, what is the z-score corresponding to a score that is 5 points below the mean?
z= -.50
Which of the following z-score values represents the location farthest from the mean?
z= -2.00