In an effort to increase sales, a company is considering a new training program for its salesdepartment. An advertisement claims that the training program leads to a mean increase of $5000 inmonthly sales. To study the program's effectiveness, the company selects 20 sales representatives,randomly assigning 10 to the training program and 10 to serve as control. On average, therepresentatives who participated in the training brought in $8231 more in monthly sales than thecontrol, and the 95% confidence interval for the difference in means was (2799, 13663) dollars.Does this confidence interval provide convincing statistical evidence that the mean increase in salesis different from the advertised value?(A) No, because $0 is outside the interval the results are not statistically significant.(B) No, because $5000 is included in the interval the results are not statistically significant.(C) Yes, because $0 is outside the interval the results are statistically significant.(D) Yes, because the representatives were randomly assigned and $8231 is different from $5000.(E) Yes, because $8231 is inside the confidence interval the results are accurate.

The objective of the question is to determine whether the 95% confidence interval provides…

Answered: In an effort to increase sales, a…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Dr. Mackintosh believes a new olfactory therapy would be more successful in promoting weight loss among obese patients. His patients are first weighed and then randomly assigned to olfactory therapy, dance therapy, or a control condition. At the end of the three weeks, the amount of weight lost is recorded. The results indicate no significant difference in the amount of weight lost between the three conditions. Identify the independent variable along with each level and the dependent variable.
A recent study on driving behavior examined whether the combination of high driving skills and low safety skills is dangerous. Participants were classified as high or low in driving skill based on responses to a driver-skill inventory, then classified as high or low in safety skill based on responses to a driver-aggression scale. An overall measure of driving risk was obtained by combining several variables such as number of accidents, tickets, tendency to speed, etc. The following data were obtained. Use a 2 x 2 ANOVA with the .05 significance level to evaluate the results. What cutoff score(s) should be used? Driving Skill Low High Safety Skill Low M1=5 M2=4.5 S1=2.7 S2=3.8 N1=6 N2=6 HIgh M3=3 M4=3.5 S3=2.9 S4=2.5 N3=6 N4=6 Group of answer choices +4.35 +3.40 +3.49 +4.26
The dean of students at a large college is interested in learning about their opinions regarding the percentage of first-year students who should be given parking privileges in the main lot. He sends out an email survey to all students about this issue. A large number of first-year students reply but very few sophomores, juniors, and seniors reply. Based on the responses he receives, he constructs a 90% confidence interval for the true proportion of students who believe first-year students should be given parking privileges in the main lot to be (0.71, 0.79). Which of the following may have an impact on the confidence interval, but is not accounted for by the margin of error? response bias O nonresponse bias O sampling variation O undercoverage bias
Recent research indicates that the effectiveness of antidepressant medication is directly related to the severity of the depression (Khan, Brodhead, Kolts & Brown, 2005). Based on pretreatment depression scores, patients were divided into four groups based on their level of depression. After receiving the antidepressant medication, depression scores were measured again and the amount of improvement was recorded for each patient. The following data are similar to the results of the study. Low High Moderate Moderate Moderately Severe Severe 0 2.6 2.7 2.7 1.7 2.5 3.2 3.3 2.2 3 3.2 5.2 0.6 1.8 3.8 1.5 1.9 1.9 3.8 5.9 1.3 1.2 2.4 2.9 From this table, conduct an one-way ANOVA. Calculate the F-ratio and p-value. Be sure to round your answers to three decimal places. Assume all population and ANOVA requirements are met. F-ratio: p-value: What is your final conclusion? Use a significance level of απ 0.02. There is not enough evidence to determine a difference between the treatments. There is…
Find a 95% confidence interval for the percentage of stocks with a gain.
A general merhandise chain store wants to know if two if its local stores’ sales profiles are similar to that of the general chain. The general daily revenue of the chain is $ 93.5 daily (in thousands) per store. The chain is tracking the sales of each store. The CEO sends two accountants to the stores below to quantify with 95% confidence whether Store A has less sales and store B has more sales in comparison to the general chain’s store profile For the following questions assume that the overall standard deviation is equal to $8 and the chain has data from 100 samples. The chain decides to generalize the inspection scheme and settles for a lenient comparison threshold of 90% confidence. Find a confidence interval of daily revenue for the stores of the entire chain. For a randomly selected store, on a randomly selected date, what is the probability of having a revenue larger than $ 95 ? On a randomly selected date, for a randomly selected store, at most how much revenue is expected…
You want to estimate the average difference in the number of complaints filed by women at work and the number of complaints filed by men at work. You took an SRS of 7 businesses and collected the following data for number of complaints in a year: men 1 3 2 4 6 3 5 women 8 7 6 3 5 12 15 Create a 90% confidence interval for the average difference in the number of complaints filed by women at work and the number of complaints filed by men at work (in a year). You must do this using table C. If this is a 2 sample interval, be sure to specify who is population 1 and who is population 2. If this is a matched pairs interval, be sure to state the order you subtracted your data. Once you create your interval, give a sentence explaining the meaning of the interval (what the numbers in the interval mean, NOT the meaning of 95%) in context of this problem. Round to any appropriate number of decimals.
People tend to evaluate the quality of their lives to others around them. In a demonstration of this phenomenon, Frieswijk, Buunk, Steverink, and Slaets (2004) conducted interviews with frail elderly people. In the interview, each person was compared with fictitious others who were worse off. After the interviews, the elderly people reported more satisfaction with their own lives. Following are hypothetical data similar to those obtained in the research study. The scores are measures of a life-satisfaction scale for a sample of n=9 elderly people who completed the interview. Assume that the average score on this scale is u=20. Are the data sufficient to conclude that the people in this sample are significantly more satisfied than others in the general population? Use a one-tailed test with a=0.05. The life satisfaction scores are 18, 23, 24, 22, 19, 27, 23, 26, 25. Do the 4-step procedure to know your answer. You can answer either a "Yes" or "No". Answer:
Mandrake Falls High School is experimenting with a weekend course in laboratory techniques. Of the 200 students enrolled in lab classes at Mandrake, only 78 have been able to take the techniques course. Mandrake is interested in evaluating the course's effectiveness in propagating safety in the laboratories. During regular lab classes, lab instructors have recorded harmful lab incidents: accidents, misuse of lab equipment, etc. The school is looking at the data and examining two variables: laboratory performance ("involved in no incident", "involved in exactly one incident", or "involved in 2+ incidents") and status regarding lab techniques course ("took the techniques course" or "didn't take the techniques course"). The contingency table below gives a summary of the data that have been gathered so far. In each of the 6 cells of the table are three numbers: the first number is the observed cell frequency (f); the second number is the expected cell frequency (E) under the assumption…
A major company would like to assess the impact of using a professional trainer to conduct a confidence-building workshop with its salespeople. A sample of 16 workers is obtained. Half (n = 8) attend the workshop and the other half (n = 8) serve as a control group. Two weeks later, each of the participants is given a questionnaire measuring the level of self-confidence. The data are as follows: Controls Workshop M = 17.5 M = 22.7 SS = 100 SS = 124 What type of t-test would you have to conduct in this scenario? Are the data sufficient to conclude that the treatment has a significant effect? Use a two-tailed test with α = .05. State the hypothesis, find the critical region, calculate your test statistic, evaluate your hypothesis then calculate the Cohen’s d measure for this scenario. State whether this is a weak, moderate, or strong effect.
A research firm regularly conducts customer satisfaction surveys for an amusement park. A survey of 200 randomly selected park visitors on a weekday in May concluded the average age of visitors to the park was 39 years. When the survey was repeated with 200 randomly selected park visitors on a Saturday in May, the average age of visitors to the park was determined to be 17 years. Does the information represents a quantitative or qualitative variable? What is the age of the visitor? Does the visitor have a season pass?
A researcher uses matched-subjects design to investigate whether single people with pets vary in their happiness level compared to singles without pets. A mood inventory survey is given to a group of 20- to 29-year-old non-pet owners and a similar age group of pet owners. The pet owners are matched one to one with the non-pet owners for income, number of close friendships, and general health. Is there a significant difference in the mood scores for non-pet owners versus pet owners. Test with a =.05 for two tails.

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