Psych Test 3
For 25 degrees of freedom, the critical value of chi-square cutting off 5% of the upper tail is χ2 (25) = 37.65. The critical value of chi-square for the same degrees of freedom that cuts off 1% of the upper tail will be:
a larger value
A larger effect size indicates that there is \_\_\_\_\_\_______ overlap of two distributions
less
Is the following statement true or false? "A 90% confidence level can be interpreted to mean that 90% of residents of New York City have given between $10-$20 to homeless persons."
false
The probability associated with F(7,5) = 10.46 is
0.01
Your poll of 457 voters indicates that 48% of people in your state favor a return of the death penalty. Calculate the standard error for proportions.
0.023
What is the proportion in one tail associated with a t-score of 1.725 with df=20?
0.05
With alpha set to .05 the probability of rejecting the null hypothesis when it is true is \_\_\_\_\_.
0.05
Your poll of 360 randomly selected Utah residents indicates that 56% would vote Republican in the next Presidential election. What is your margin of error for the 95% level of confidence?
0.051
What is the probability associated with a z-score that is ≥ 1.42?
0.0778
For the previous question, calculate the upper and lower limits of your confidence interval that you would fill into the following statement: "We can be confident that the mean IQ score in our community lies between _________ and
106 and 110
The critical value of F(5,4) that cuts off the upper 2.5% of the distribution's tail is
15.522
Determine the critical value for a 99% confidence level; make sure to use two decimal places.
2.58
What is the critical value of z for the 99% confidence level?
2.58
A common Gallup poll question asks Americans whether they would like to see handguns banned. A recent poll indicated that 27% of those polled by Gallup said "Yes." Calculate the margin of error for that figure, assuming a 95% confidence level and a sample size of 1,000 respondents. (Only input the number)
2.7
Professor Anthony calculated a chi-square statistic of 16.22 with df=8. What is the critical value of chi-square in order to test whether or not outcome falls within the upper 1% of the distribution?
20.09
Recall the chapter example which described the fact that the mean IQ in large, diverse populations is 100 and the standard deviation is 15. Your sample of 300 members of your community gave you a mean IQ score of 108. Calculate the margin of error for the 99% confidence level for this sample. Which of the following figures comes closest to your answer
near +/- 2.23
The value of the t-statistic ranges from ∞
negative infinity to positive infinity
When alpha increases, both \_\_\_\_\_\_______ and \_\_\_\_\_\_______ increase
power; probability of type I error
It becomes progressively easier to declare statistical significance as we increase what?
sample size
The gap between a statistic and its corresponding parameter is known as
sampling error
Match the following distributions with the situations in which we would use them small sample known population standard deviation or large sample match with (t and z)
small sample = t
Standard scores share a common distribution with a common mean and
standard deviation; variance
The symbol σx̅ represents the ___ of the mean
standard error
Which of the following is not actually a family of distributions?
standard normal distribution
A study of the habits of those who admit texting while driving has a single group of 25 participants. The dependent variable is reaction time to detect a sound, with a sample mean of 635 ms with a standard deviation of 143 ms. This test has a population mean of 600 milliseconds. Which test would be most appropriate to find the probability of obtaining this sample mean?
t
Which of the following is a characteristic of skewed distributions such as chi-square and F? A Only the upper tail is of interest to statisticians B They tend to pile up against an absolute upper limit C They never approach normalcy D The critical values cutting off the identical areas of the upper and lower tails have differing absolute values
the critical values cutting off the identical areas of upper and lower tails have differing absolute values
Alpha refers to _
the probability of making type I error
Monte Carlo experiments established that sample size is related to which of the following?
the shape of the distrubtion
What is Cohen's d?
the standardized difference between group means
Confidence Intervals assume that you have used simple random sampling
true
Most real-world hypotheses are non-directional.
true
The statement, H1: µ ≠ k, would require a ___ -tailed test
two
The F-ratio is a ratio of
two variances
Tables of critical values help to determine the probability a measure occurred by
chance
The null and alternative hypotheses must be
complementary
The z, t, and F calculations have something in common: the denominator of the test statistic
contains a measure of sample variability
The F-table lookup procedure involves using two known values for _
degrees of freedom
Cohen's d is one measure of _
effect size
Cohen's d measures the difference between means in terms of \_\_\_\_\_\_\_._______. (2 words for one statistical term)
effect size, or standard deviation
Is the following statement true or false? "A 95% confidence level can be interpreted to mean that 95% of all households in the UK earned between 30,000 GBP and 45,000 GBP last year."
false
The standard normal distribution is really a family of distributions.
false
The value of chi-square can be negative.
false
The rationale for degrees of freedom is that one value in a set of values with a known result is not
free to vary
Which of the following hypotheses would be used for a two-tailed test?
homicide rates vary according to size of city
That a result is statistically significant does not mean that it is
important in real world
What does increasing the sample size do?
increase liklihood that we will reject the null hypothesis
As alpha increases, power
increases
The effect of changing the sample size is rooted in the law of \_\_\_\_\_\_\_\_________ \_\_\_\_\_\_\_\_\__________, which tells us that the larger our sample size, the less sampling error there is likely to be.
large numbers
What is the critical value of z for the 95% confidence level?
1.96
Your master's dissertation concerns recent immigrants' experiences of severe financial strain. A large sample of 960 residents of a medium-sized city indicated that 80% of new immigrants felt that they were extremely stressed financially (which was higher than what is average for the general population.) If you were to construct a 99% confidence interval for your finding, what would be the UPPER LIMIT of the interval (written as a proportion to 3 decimal places, rather than a percentage)?
0.833
With alpha set to .05 the probability of failing to reject the null hypothesis when it is true is
0.95
The class mean on Exam 2 is 72.8 with a standard deviation of 12.8. There are 20 students in the class. What is the 95% confidence interval?
66.81, 78.79
Construct the confidence interval that will be narrower than the 95% confidence interval constructed in 8.41 using the same information. In that problem, the class mean on Exam 2 is 72.8 with a standard deviation of 12.8. There are 20 students in the class.
67.86, 77.74
The lowest level of confidence that is conventionally used with large samples is ___%
90
Hypothesis testing tells us which of the following? A What the size of an effect is B Which group differences are of practical importance C Whether two distributions overlap at all D What results are significant, but it does not indicate anything about the importance of significant results
D
Pretend that you are a Project Manager for a local survey research firm. Your firm has been hired by your city council to ask residents a short survey about local issues, such as whether they supported a proposed by-law which required cat owners to purchase a license for their pet. Your surveys tend to cost $10 per respondent. Which of the following options would you choose? A Sample size of 250, for a margin of error of ±3.5% at the 95% level B Sample size of 500, for a margin of error of ±4.5% at the 99% level
A
sort following alpha levels from smallest to largest rejection region C .08 2 B .05 3 A .01
A B C
So far, you have stated your claim and identified your null and alternative hypotheses. Sort the following steps that come next, before making your final interpretations. 1 B Choose the appropriate test statistic. 2 A Specify the level of significance. 3 E Calculate the test statistic using data from the sample. 4 C Identify the critical value of the test statistic. 5 D Compare the calculated statistic to the critical value and decide to reject of fail to reject the null hypothesis.
A B C E D
A graduate student has determined that for her research, β = .75. What does this suggest? (Select all that apply) A She has a high probability of a Type II Error. B She has a high probability of a Type I error. C The power of her experiment is high. D It is likely that she has missed an effect that truly exists
A and D
When we report that something is statistically significant, it means that which of the following is true? A There is no way for the null hypothesis to be true B The findings are unlikely to occur if the null hypothesis is true C The research hypothesis is true and the results are unlikely to be repeated D The findings are likely to occur if the null hypothesis is false
B
Sort the following steps for writing a hypothesis statement according to the order in which you should perform them.
B Identify the populations. 2 A Identify the independent and dependent variables and operationally define them. 3 C Identify the Effect.
Hypothesis testing alone may oversimplify results. Which of the following is a way to enhance our analysis A Select another comparison distribution B Statistical power analyses C Effect size calculations
B and C
Tables of critical values can be used to determine
The probability associated with a range of values
The chi-square and F-distributions are ________ skewed.
positively
Non-negative values are likely in which distributions? A Standard normal B t C chi ^2 D F
all the above
The z-score distribution ________ has a mean of
always; 0
Which of the following would be indicated by a negative value for F? A A correspondingly low probability B A tt-table could have been used instead C An error in the calculations D A reversal of the expected variation
an error in calculation
Measures of effect size
are unaffected by sample size
Pretend that you have an limited budget of $500 to study the relationship between social class and voting preferences. Due to such a small budget you can survey only 50 people from a simple random sample. If your budget were to increase to $3000, allowing you to survey many more people from a simple random sample, your test statistic would likely:
become larger
Statistical power refers to the probability of correctly rejecting the \_\_\_\_\_\_\_.
null hypothesis
Confidence intervals are based on the idea that it is relatively rare for us to have a known
parameter
In the previous question (wherein Professor Anthony calculated a chi-square statistic of 16.22 with df=8), would his outcome fall within the upper 5% of the distribution?
yes
A social sciences researcher wants to know about the amount of money that couples without children spend on leisure travel. Her sample of 280 couples yields a mean of $1263.00 and a standard deviation of $160.00. What is the margin of error for a 95% confidence interval?
$18.74
Suppose that your sample of 50 registered voters has a mean age of 52 years and a standard deviation of 10 years. What would be your margin of error at the 90% confidence level?
+/- 2.33 years
A graduate student has determined that for her research, β = .75. What is the power of her experiment?
0.25
According to Cohen's conventions, an average effect size is d =
0.5
Your poll of 360 randomly selected Utah residents indicates that 56% would vote Republican in the next Presidential election. What is your margin of error for the 99% level of confidence?
0.067
This question is similar to EOC 8.34. Your master's dissertation concerns recent immigrants' experiences of severe financial strain. A large sample of 960 residents of a medium-sized city indicated that 80% of new immigrants felt that they were extremely stressed financially (which was higher than what is average for the general population.) If you were to construct a 99% confidence interval for your finding, what would be the LOWER LIMIT of the interval (written as a proportion to 3 decimal places, rather than a percentage)?
0.767
According to Cohen's conventions, a d value of \_\_\_\_\_\_\________ indicates a large effect
0.8
For the previous example, calculate the upper and lower limits of your confidence interval that you would fill into the following statement of interpretation: "We can be confident that the percentage of Americans who support a ban on handguns is between \_\_\_\_\_\_\_\_\_\_\_\_\______________ and \_\_\_\_\_\_\_\_\_\_\_\_\_
24.3 and 29.7
You are concerned with the amount of time that teens spend doing online gaming, and you measure a random sample of 32 high school students with a mean of 28.6 hours per week. In calculating t-statistics, how many degrees of freedom (df) do you have?
31.0
The critical value of chi ^2 (df=25) cutting off 5% of the distribution is
37.65
A psychology instructor was interested in seeing whether students who had completed a basic math course prior to taking the department's introductory statistics course scored differently on the placement test for the statistics course. She collected data on two samples of students and found that 16 students who had completed the math course had a mean score of x̅1 = 58.6 with σ = 3.4 and 18 students who did not take the math course had a mean score of x̅2 = 44.4 with σ = 3.2. Compute the effect size using Cohen's d for these data.
4.3
If we have a normally distributed sample of ages ranging from 1 to 99 years, and we draw a score at random from this distribution, which of the following scores would we be most likely to draw?
47
A university professor finds that the mean for 20 students who sought out tutoring for an exam was 78.9 (s = 15). The mean for the 20 students who did not seek tutoring was 72.6 (s = 13). What is the absolute effect size?
6.3
Which of the following is an example of an interval estimate? (Select all that apply) A 9 out of 10 professors encourage outside reading. B 46% to 61% of students believe parking at the university could be improved. C 15% to 25% of commuters prefer trains over busses. D 72% of parents support television programs for toddlers.
B and C
Which of the following are never negative? (Select all that apply) A z B t C F D χ2
C and D
There is a different F-distribution for every
Combination of degrees of freedom
Sort the following four steps for calculating a confidence interval into their correct order.
D Select a sample statistic (a sample mean) 2 A Select a desired confidence level (typically 95% or 99%) and determine the appropriate critical value. 3 B Determine the margin of error using the standard error of the mean. 4 C Specify the upper and lower limits of the confidence interval.
Confidence Intervals can be used for any type of distribution.
false
As the confidence level increases, what happens to the margin of error?
increases
Your hypothesis for a longitudinal study states: "The higher a country's female literacy rate, the lower its birth rate will be in subsequent years." In this example, female literacy rate is the __________ variable. (Select all that apply)
independent, predictor
The statement "The findings based on a sample of 1000 participants were statistically significant, providing evidence for our hypothesis" would be strengthened by
measuring effect sizes
Professor Johnson investigates the difference between job satisfaction in two groups of employees, one of whom received online training workshops while the others attended in-person workshops. He calculates Cohen's d as .40. He classifies this effect size as
medium
In hypothesis testing, which of the following is a statement about the population parameter that is assumed to be true by default?
null
Chi-square distributions are (check all that apply)
positively skewed
What is the probability we will not make a Type II error?
statistical power
The alternative hypothesis can never be proved in a single experiment.
true
