Poissson distribution

In order to control the polishing quality of a lens, a certain company is used to finish the number of spots on the surface considering the defective lens if 3 or more spots appear on it. The average rate is 2 defects per cm2. Calculate the probability that a 4cm2 lens will not be classified as defective.

The health of the bear population in a park is monitored by periodic measurements taken from anesthetized bears. A sample of the weights of such bears is given below. Find a​ 95% confidence interval estimate of the mean of the population of all such bear weights. The​ 95% confidence interval for the mean bear weight is the following.

data table 80 344 416 348 166 220 262 360 204 144 332 34 140 180

We are attempting to see if we can justify the additional expense of premium fuel over economy; i.e., we will only use premium fuel if we are convinced that it actually helps mpg. For each of the 25 cars at our disposal, we randomly picked one fuel to use first, drove the car until nearly empty, and calculated mpg when refilling the tank. We then filled it with the other fuel, repeating the process, obtaining mpg for that fuel, driving over the same roads.  

Explain why it would be important to randomize the order in which we test two gasoline types. Give a specific example of how not randomizing might cause a problem with this design.

PART 1: Determining the Appropriate Test

Assume that the following three questions appeared on a survey that is being used to collect data on consumer behavior for your company.

Question 1:         Do you subscribe to Netflix? (Circle One)                               YES         NO

Question 2:         What is your monthly average income in dollars?               $__________

Question 3:         In which of the 5 U.S. regions do you reside? (Circle one)

                                Northeast           Southwest          West          Midwest        Southeast

1. You want to determine if a relationship exists between the U.S. region in which the consumer resides and whether or not they are a subscriber to Netflix.

1. Which test should you run to help you answer this question? (ANOVA or Chi-Square test)

2. Given your answer in part “A” above, set up the null and alternative hypotheses to begin your test.

2. Now assume that you want to determine if the average monthly income of a consumer is different among groups of people living in different regions of the United States.

1. Which test should you run to help you answer this question? (ANOVA or Chi-Square test)

2. Given your answer in part “A” above, set up the null and alternative hypotheses to begin your test.

PART 2: Analysis of a Chi-Square test

Assume that a research study was conducted that included the following survey questions:

Question 1:         Have you ever attended an event at the city Performing Arts Center?       YES         NO

Question 2:         Have you ever attended an event at the city Athletic Center?                       YES         NO

A sample of 93 people answered the survey questions. The research team utilized Minitab statistical software to create the results shown below. You will find a contingency table with the Chi-Square test statistic and p-value at the bottom.

---------------------------------------------------------------------------------------------------------------------------------

CHI-SQUARE TEST FOR ASSOCIATION: PERFORMING ARTS CENTER ATTENDANCE, ATHLETIC CENTER ATTENDANCE

Rows: Performing Arts Center Attendance                        Columns: Athletic Center Attendance

Cell Contents:                        Count

                                                Expected Count   

Review the study and the Minitab results. Then answer the following questions:

1. If you want to determine if a relationship exists between whether or not a person attended an event at the Performing Arts center and whether or not the person attended an event at the Athletic Center, set up the null and alternative hypotheses to begin your test.

2. Find the p-value in the output. Draw a conclusion about your hypotheses based on this p-value. Be sure to explain your answer. Why did you draw the conclusion that you did?

The next two questions (7 and 8) refer to the following:

The weight of bags of organic fertilizer is normally distributed with a mean of 60 pounds and a standard deviation of 2.5 pounds.

7. What is the probability that a random sample of 33 bags of organic fertilizer has a total weight between 1963.5 and 1996.5 pounds?

8. If we take a random sample of 9 bags of organic fertilizer, there is a 75% chance that their mean weight will be less than what value? Keep 4 decimal places in intermediate calculations and report your final answer to 4 decimal places.

The next two questions (8 and 9) refer to the following:

Question 10 and 11

Suppose that 40% of students at a university drive to campus.

10. If we randomly select 100 students from this university, what is the approximate probability that less than 35% of them drive to campus?

Keep 6 decimal places in intermediate calculations and report your final answer to 4 decimal places.

11. If we randomly select 100 students from this university, what is the approximate probability that more than 50 of them drive to campus?

Keep 6 decimal places in intermediate calculations and report your final answer to 4 decimal places.

12. Suppose that IQs of adult Canadians follow a normal distribution with standard deviation 15. A random sample of 30 adult Canadians has a mean IQ of 112.

We would like to construct a 97% confidence interval for the true mean IQ of all adult Canadians. What is the critical value z* to be used in the interval? (You do not need to calculate the calculate the confidence interval. Simply find z*. Input a positive number since we always use the positive z* value when calculating confidence intervals.)

Report your answer to 2 decimal places.

Components of a certain type are shipped to a supplier in batches of ten. Suppose that 51% of all such batches contain no defective components, 33% contain one defective component, and 16% contain two defective components. Two components from a batch are randomly selected and tested. What are the probabilities associated with 0, 1, and 2 defective components being in the batch under each of the following conditions? (Round your answers to four decimal places.)

(a) Neither tested component is defective.

no defective components :

one defective component :

two defective components :

(b) One of the two tested components is defective. [Hint: Draw a tree diagram with three first-generation branches for the three different types of batches.]

no defective components :

one defective component :

two defective components :

The FBI wants to determine the effectiveness of their 10 Most Wanted list. To do so, they need to find out the fraction of people who appear on the list that are actually caught.

Step 2 of 2 :  

Suppose a sample of 362 suspected criminals is drawn. Of these people, 119 were captured. Using the data, construct the 90% confidence interval for the population proportion of people who are captured after appearing on the 10 Most Wanted list. Round your answers to three decimal places.

*Repeated Measures Analysis of Variance*
Examining differences between groups on one or more variables / same participants being tested more than once / with more than two groups.

What test and method would be used to examine the difference between male and female users considering the different variable (Pain Reliever, Sedative, Tranquilizer & Stimulant)

Create a graph illustration.

Describe the Graph.

Workers in several industries were surveyed to determine the proportion of workers who feel their industry is understaffed. In the government sector, 37% of the respondents said they were understaffed, in the health care sector 33% said they were understaffed and in the education sector 28% said they were understaffed (USA Today, January 11, 2010). Suppose that 200 workers were surveyed in each industry.

b) Assuming the same sample size will be used in each industry, how large would the sample need to be to ensure that the margin of error is 5% or less for each of the three confidence intervals? Perform the calculation using an appropriate pilot study proportion as well as a worst case scenario.

Determine and interpret the linear correlation coefficient, and use linear regression to find a best fit line for a scatter plot of the data and make predictions. Scenario According to the U.S. Geological Survey (USGS), the probability of a magnitude 6.7 or greater earthquake in the Greater Bay Area is 63%, about 2 out of 3, in the next 30 years. In April 2008, scientists and engineers released a new earthquake forecast for the State of California called the Uniform California Earthquake Rupture Forecast (UCERF). As a junior analyst at the USGS, you are tasked to determine whether there is sufficient evidence to support the claim of a linear correlation between the magnitudes and depths from the earthquakes. Your deliverables will be a PowerPoint presentation you will create summarizing your findings and an excel document to show your work. Concepts Being Studied • Correlation and regression • Creating scatterplots • Constructing and interpreting a Hypothesis Test for Correlation using r as the test statistic You are given a spreadsheet that contains the following information: • Magnitude measured on the Richter scale • Depth in km Using the spreadsheet, you will answer the problems below in a PowerPoint presentation. What to Submit The PowerPoint presentation should answer and explain the following questions based on the spreadsheet provided above. • Slide 1: Title slide • Slide 2: Introduce your scenario and data set including the variables provided. • Slide 3: Construct a scatterplot of the two variables provided in the spreadsheet. Include a description of what you see in the scatterplot. • Slide 4: Find the value of the linear correlation coefficient r and the critical value of r using α = 0.05. Include an explanation on how you found those values. • Slide 5: Determine whether there is sufficient evidence to support the claim of a linear correlation between the magnitudes and the depths from the earthquakes. Explain. • Slide 6: Find the regression equation. Let the predictor (x) variable be the magnitude. Identify the slope and the y-intercept within your regression equation. • Slide 7: Is the equation a good model? Explain. What would be the best predicted depth of an earthquake with a magnitude of 2.0? Include the correct units. • Slide 8: Conclude by recapping your ideas by summarizing the information presented in context of the scenario. Along with your PowerPoint presentation, you should include your Excel document which shows all calculations.

The table below summarizes baseline characteristics of patients participating in a clinical trial. a) Are there any statistically significant differences in baseline characteristics between treatment groups? Justify your answer.

b) Write the hypotheses and the test statistic used to compare ages between groups. (No calculations – just H0, H1 and form of the test statistic).

c) Write the hypotheses and the test statistic used to compare % females between groups. (No calculations – just H0, H1 and form of the test statistic).

d) Write the hypotheses and the test statistic used to compare % females between groups. (No calculations – just H0, H1 and form of the test statistic.) Characteristic Placebo (n = 125) Experimental ( n =125) P Mean (+ SD) Age 54 + 4.5 53 + 4.9 0.7856 % Female 39% 52% 0.0289 % Less than High School Education 24% 22% 0.0986 % Completing High School 37% 36% % Completing Some College 39% 42% Mean (+ SD) Systolic Blood Pressure 136 + 13.8 134 + 12.4 0.4736 Mean (+ SD) Total Cholesterol 214 + 24.9 210 + 23.1 0.8954 % Current Smokers 17% 15% 0.5741 % with Diabetes 8% 3% 0.0438

The director of Human Resources at a large company wishes to determine if newly instituted training has been effective in reducing work-related injuries. In a random sample of 100 employees taken from the six months before this training began (group 1), she found 15 had suffered a work-related injury. Using a random sample of 150 employees from the six months since the training began (group 2), she found 12 had suffered a work-related injury.
a) Find the 95% confidence interval for this situation.  

b) Does it support the idea that the proportion of work-related injuries has decreased with the new training?

Show work - label all your values first before using technology.

Brooke is moving out of her parents’ house into her first apartment. While packing she realizes she has a lot of shoes – 42 pair, in fact. She wonders if most women have as many shoes as she does, so for her experimental psychology project she sends surveys to120 women from her college and asks how many pairs of shoes they have. She finds that, on average, the women have15 pair of shoes (sd =2.50). Given this information, does Brooke have statistically more shoes than women in general? Complete the six steps of hypothesis testing by hand and perform the appropriate statisticaltest using SPSS. Then, writean APA formatted 4-part results section.

The resting pulse rate of a simple random sample of 9 women was recorded yielding a mean resting pulse rate of 76 beats per minute with standard deviation 5. Use this information for this question and the next one. The p-value of a statistical test where the alternative hypothesis is that the mean resting pulse rate is greater than 72 is:
(a) Between 0 and 0.01
(b) Between 0.01 and 0.025
(c) Between 0.025 and 0.05
(d) Between 0.05 and 0.1
(e) Greater than 0.1
The resting pulse rate of a simple random sample of 9 women was recorded yielding a mean resting pulse rate of 76 beats per minute with standard deviation 5. What is a 95% confidence interval for the mean resting pulse rate?
(a) [72.16;79.84]
(b) [72.73;79.27]
(c) [72.9;79.1]
(d) [73.26;78.74]
(e) None of the above.

To evaluate the effect of a treatment, a sample is obtained from a population with a mean of μ = 20 and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be M = 21.3 with a variance of s2 = 9. a. Assuming that the sample consists of n = 16 individuals, use a two-tailed test with α =0.05 to determine whether the treatment effect is significant and compute both Cohen's d and r2 to measure effect size. are the data sufficient to conclude that the treatment has a significant effect ? b. Assuming that the sample consists of n = 36 individuals, repeat the test and compute both measures of effect size? c. Comparing your answers for parts a and b, how does the size of the sample influence the outcome of a hypothesis test and the measurement of effect size?