A professor wants to know whether or not there is a difference in comprehension of a lab assignment among students depending on if the instructions are given all in text, or if they are given primarily with visual illustrations. She randomly divides her class into two groups of 15, gives one group instructions in text and the second group instructions with visual illustrations. The following data summarizes the scores the students received on a test given after the lab. Let the populations be normally distributed with a populations standard deviation of 5.32 points for both the text and visual illustrations.

Is there evidence to suggest that a difference exists in the comprehension of the lab based on the test scores? Use α=0.10.

Enter the test statistic - round to 4 decimal places.

Enter the P-Value - round to 4 decimal places.

Can it be concluded that a difference exists in the comprehension of the lab based on the test scores?

Directions: For each of the following studies, state both the null and alternative hypotheses and the decision rule, then work the problem. Look up the critical value of t that would cut off the tails of the distribution. Note that each study specifies the alpha value to use and whether to use a one- or two-tailed test. Decide whether to reject or fail to reject the null and answer the question. Please copy and paste the text into a document and include your answers in bold font.

There is no sample size for the first example. I will take whatever I can get to help solve

1. Sommer (1999) investigated student satisfaction with distance learning. One group of students took Introductory Psychology over the Internet and another group took the course in the usual classroom lecture format. Students rated their satisfaction with the course on a scale from 1 (not at all satisfied) to 9 (extremely satisfied). Sommer found that students in the distance learning condition had an average satisfaction of 4.33, with a standard deviation of 2.94, whereas students in the classroom format reported a mean satisfaction of 6.67 and a standard deviation of 0.82. State your null hypothesis, use α = 0.05 for a nondirectional test, and report your critical value. Is there a difference between the groups?

2. Wilson (1999) studied impulse control in grade-school children. She studied 25 average third-graders and found a failure of impulse control 4.6 times per day, with a standard deviation of 2.1 times per day. Wilson also studied 36 third-graders diagnosed with ADHD and found that they showed failures of impulse control on average 7.2 times per day, with a standard deviation of 3.1. State your null hypothesis, use α = 0.01 for a directional test, and report your critical value. Do third-graders with ADHD have more trouble with impulse control?

Loftus and Palmer study (1974) demonstrated the influence of language on eyewitness memory. Participants watched a film of a car accident and were asked questions about what they saw. One group was asked “About how fast the cars were going when they smashed into each other?” Another group was asked the same question, except the verb was changed to “hit” instead of “smashed into”. The ‘smasher into” group reported significantly higher estimates of speed than the hit group. Suppose a researcher repeats this study with two samples of college students and obtains the following results:

Is there a significantly higher estimated speed for the “smashed into” group? Use a one-tailed test with α = .01.

a) The t-statistic is

b) Your decision is:

c)The estimated Cohen's d is:

d)The critical t value is

An Office of Admissions document claims that 56.1% of UVA undergraduates are female. To test whether this claim is accurate, a random sample of 220 UVA undergraduates was selected. In this sample, 53.6364% were female. Is there sufficient evidence to conclude that the document's claim is false? Carry out a hypothesis test at a 10% significance level.

A. The p-value is

B. Your decision for the hypothesis test:

A. Do Not Reject H1H1.
B. Reject H0H0.
C. Reject H1H1.
D. Do Not Reject H0H0.

Also, can you do the calculations for finding the p-value on TI-83? Thanks!

Isle Royale, an island in Lake Superior, has provided an important study site of wolves and their prey. Of special interest is the study of the number of moose killed by wolves. In the period from 1958 to 1974, there were 296 moose deaths identified as wolf kills. The age distribution of the kills is as follows.

(a) For each age group, compute the probability that a moose in that age group is killed by a wolf. (Round your answers to three decimal places.)

(b) Consider all ages in a class equal to the class midpoint. Find the expected age of a moose killed by a wolf and the standard deviation of the ages. (Round your answers to two decimal places.)

According to the Centres for Disease Control, 15.2% of American adults experience migraine headaches. Stress is a major contributor to the frequency and intensity of headaches. A massage therapist feels that she has a technique that can reduce the frequency and intensity of migraine headaches.

(a) Determine the null and alternative hypotheses that would be used to test the effectiveness of the massage therapists techniques.

(b) A sample of 500 American adults who participated in the massage therapists program results in data that indicate that the null hypothesis should be rejected. Provide a statement that supports the massage therapists program.

(c) Explain what it would mean to make Type I error.

(d) Explain what it would mean to make a Type II error.

Listed below are brain volumes (cm3 ) of twins.

Test the claim at the 5% significance level that the brain volume for the first born is different from the second-born twin.

(a) State the null and alternative hypotheses.

(b) Find the critical value and the test statistic.

(c) Should H0 be rejected at the 5% significance level? Make a conclusion.

(d) Construct a 95% confidence interval for the paired difference of the population means

A hospital administrator has been asked by her supervisor to assess whether waiting time in the emergency room (ER) has changed from last year, when average wait time was 127 minutes. The administrator collects a simple random sample of 64 patients and records the time between when they checked in at the ER until they were first seen by a doctor; the average wait time is 137 minutes, with standard deviation 39 minutes.

a) Compute and interpret a 95% confidence interval for mean ER wait time at the hospital. Based on the interval, is mean ER wait time statistically significantly different from 127 minutes at the α = 0.05 level?

2. b) Would the conclusion in part a) change if the significance level were changed to α = 0.01?

3. c) Suppose that upon seeing the results from part a), the supervisor criticizes the hospital administrator on the basis that ER wait times have increased greatly from last year and the administrator must be at fault. Present a brief argument in favor of the administrator.

Puppies were sorted into three groups, based upon which food they preferred when given a choice: Brand A puppy food, Brand B puppy food, or a diet of cooked ground meat. For two months, each group was restricted to its preferred diet (they were no longer given a choice in diet). Measurements for the height, weight, and length of the puppies was taken each week for two months. The puppies in the group with the diet of cooked ground meat had significantly more growth than the other two groups.

What conclusion can be drawn from this study?

A. There is a causal relationship between diet and puppy growth.

B. No conclusions can be made because there was not a group that received a placebo.

C. It is not possible to make any conclusions because there could be lurking variables that were not considered that caused the difference in growth.

D. There is clear evidence of an association between diet and puppy growth, but it cannot be said there is a causal relationship between diet and puppy growth.

I know the answer is D, my question is why?

Psychologists question the importance of biodiversity on the psychological health of humans in urban areas. Urban residents often visit green spaces such as parks within urban environments. Fuller et al., conducted a study on 15 different green spaces to determine the impacts of green space on people's psychological health.

To assess how much people liked the green space, scientists had participants fill out a survey to determine their attachment to the green space. Scientists then then quantified the biodiversity of birds, plants, and butterflies at the different green spaces.

Here is a link to a dataset relating biodiversity to residents' attachment to a location.

Which biodiversity measurement (butterfly species; bird species; plant species) variable is most strongly correlated with residents' "attachment"?  

Calculate the correlation coefficients using the =correl() function in Excel.

What is the standard error of that correlation?  

Calculate your answer using Excel and report your answer to four decimal places.

Which species exhibited the weakest correlation?  

What is the correlation coefficient of the weakest relationship?  

Calculate your answer using Excel and report your answer to four decimal places.

What is the value of t for the correlation of bird species?

Report your answer to four decimal places

What is the p value associated with the t value calculated in Question 5? Use the excel formula =2*(1-(T.Dist(ABS(t,df,TRUE))))

This is a two-tailed t-test

degrees of freedom (df) = n - 2

We are using a cumulative probability function so we type TRUE

Report your answer to 4 decimal places

Based on this p value, should the authors reject or fail to reject the null hypothesis that bird species abundance is not correlated to attachment?

DATA SET

I am starting my first statistics and probability course at my university. What is the best way to study this subject and get good grades?

Because of safety considerations, in May 2003 the Federal Aviation Administration (FAA) changed its guidelines for how small commuter airlines must estimate passenger weights. Under the old rule, airlines used 180 pounds as a typical passenger weight (including carry-on luggage) in warm months and 185 pounds as a typical weight in cold months.

A journal reported that an airline conducted a study to estimate average passenger plus carry-on weights. They found an average summer weight of 183 pounds and a winter average of 190 pounds. Suppose that each of these estimates was based on a random sample of 100 passengers and that the sample standard deviations were 18 pounds for the summer weights and 25 pounds for the winter weights.

(a)

Construct a 95% confidence interval for the mean summer weight (including carry-on luggage) of this airline's passengers. (Round your answers to three decimal places.)

Interpret a 95% confidence interval for the mean summer weight (including carry-on luggage) of this airline's passengers.

There is a 95% chance that the true mean summer weight (including carry-on luggage) of this airline's passengers is one of these two values. There is a 95% chance that the true mean summer weight (including carry-on luggage) of this airline's passengers is directly in the middle of these two values.     We are 95% confident that the true mean summer weight (including carry-on luggage) of this airline's passengers is between these two values. There is a 95% chance that the true mean summer weight (including carry-on luggage) of this airline's passengers is between these two values. We are 95% confident that the true mean summer weight (including carry-on luggage) of this airline's passengers is directly in the middle of these two values.

(b)

Construct a 95% confidence interval for the mean winter weight (including carry-on luggage) of this airline's passengers. (Round your answers to three decimal places.)

Interpret a 95% confidence interval for the mean winter weight (including carry-on luggage) of this airline's passengers.

There is a 95% chance that the true mean winter weight (including carry-on luggage) of this airline's passengers is one of these two values. There is a 95% chance that the true mean winter weight (including carry-on luggage) of this airline's passengers is between these two values.     We are 95% confident that the true mean winter weight (including carry-on luggage) of this airline's passengers is between these two values. There is a 95% chance that the true mean winter weight (including carry-on luggage) of this airline's passengers is directly in the middle of these two values. We are 95% confident that the true mean winter weight (including carry-on luggage) of this airline's passengers is directly in the middle of these two values.

(c)

The new FAA recommendations are 190 pounds for summer and 195 pounds for winter. Comment on these recommendations in light of the confidence interval estimates from part (a) and part (b).

Only the new winter FAA recommendation seems accurate, since only the new winter recommendation value is contained within its 95% confidence interval. Only the new summer FAA recommendation seems accurate, since only the new summer recommendation value is contained within its 95% confidence interval.     These new FAA recommendations don't seem accurate, since neither recommendation value is contained within its respective 95% confidence interval. These new FAA recommendations seem accurate, since both recommendation values are contained within their respective 95% confidence interval.

You may need to use the appropriate table in Appendix A to answer this question.

The number of undergraduate students at the University of Winnipeg is approximately 9,000, while the University of Manitoba has approximately 27,000 undergraduate students. Suppose that, at each university, a simple random sample of 3% of the undergraduate students is selected and the following question is asked: “Do you approve of the provincial government’s decision to lift the tuition freeze?”. Suppose that, within each university, approximately 20% of undergraduate students favour this decision. What can be said about the sampling variability associated with the two sample proportions?
(A) The sample proportion for the U of W has less sampling variability than that for the U of M.

(B) The sample proportion for the U of W has more sampling variability that that for the U of M.

(C) The sample proportion for the U of W has approximately the same sampling variability as that for the U of M.

(D) It is impossible to make any statements about the sampling variability of the two sample proportions without taking many samples.

(E) It is impossible to make any statements about the sampling variability of the two sample proportions because the population sizes are different.

Could you explain why answer is (B)

What business, economic, policy, and environmental threats to organization growth are CEOs extremely concerned about? In a survey by PricewaterhouseCoopers (PwC), 57 of 114 U.S. CEOs are extremely concerned about cyber threats, and 22 are extremely concerned about lack of trust in business.

a. Construct a 95% confidence interval estimate for the population proportion of U.S. CEOs who are extremely concerned about cyber threats.

b. Construct a 95% confidence interval estimate for the population proportion of U.S. CEOs who are extremely concerned about lack of trust in business.

c. Interpret the intervals in (a) and (b).

let v and u are random variables fvu(v,u)= e^-v-u for u ,v>=0 Z= e^v+u find fz(z) ?