At one hospital in 1992, 674 women were diagnosed with breast cancer. Five years later, 88% of the Caucasian women and 83% of the African American women were still alive. Identify the study as an observational study or a designed experiment.

At one hospital in 1992, 674 women were diagnosed with breast cancer. Five years later, 88% of the Caucasian women and 83% of the African American women were still alive. Identify the study as an observational study or a designed experiment.

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

An ecology class used binoculars to watch 23 turtles at Walden Pond. It was found that 18 were box turtles and 5 were snapping turtles. What kind of study is this? -observational -census -simulation -experimental
Alcohol abuse has been described by college presidents as the number one problem on campus, and it is an important cause of death in young adults. How common is it? A survey of 10,904 randomly selected U.S. college students collected information on drinking behavior and alcohol-related problems. The researchers defined “frequent binge drinking” as having five or more drinks in a row three or more times in the past two weeks. According to this definition, 2486 students were classified as frequent binge drinkers. Construct and interpret a 99% confidence interval for the proportion of students who are classified as binge drinkers. (Use the four-step process and Table A to get your z* value.) Using the interval that you calculated in the last question, conclude in context for the question.
Seattle Grace Medical Center. As part of a long-term study of individuals 65 years of age or older, doctors at the Seattle Grace Medical Center in Washington state investigated the relationship between state of residence and depression. A sample of 60 individuals, all in reasonably good health, was selected; 20 individuals were residents of Texas, 20 were residents of Washington state, and 20 were residents of South Carolina. Each of the individuals sampled was given a standardized test to measure depression. The data collected follow; higher test scores indicate higher levels of depression. These data are contained in the attached data file SeattleGrace1. A second part of the study considered the relationship between state of residence and depression for individuals 65 years of age or older who had a chronic health condition such as diabetes and/or high blood pressure. A sample of 60 individuals with such conditions was identified. Again, 20 were residents of Texas, 20 were residents…
In a major urban area, the percentage of male drivers between the ages of 19 and 29 who did not regularly use seatbelts was 28%. After a major radio and television campaign and stricter enforcement by the local police, researchers want to know if the percentage of male drivers between the ages of 19 and 29 who did not regularly use seatbelts has decreased. They poll a random sample of 100 males between the ages of 19 and 29 and find the percentage who didn’t wear their seatbelt was 24%. (a) Identify the population, parameter, sample and statistic.(b) State appropriate hypotheses for performing a significance test.
In a survey of 1220 adults in a country, 58% said the country's leader should release all medical information that might affect their ability to serve. The study is observational, an experiment, because it applies does not apply a treatment to the adults.
Suppose you work as a manager for a large clothing store. You are considering introducing a loyalty program to encourage customers to spend more at your store. Before rolling out your program to the public, you want to do a small experiment to estimate its effectiveness. You offer the loyalty program to 10 random customers, and also observed the sales of 27 random customers who did not get the program as a control group. The customers that were part of the loyalty program had average monthly sales of $302.57 and a sample standard deviation of $49.73. For the control group, the customers had an average monthly sales of $231.65 and a sample standard deviation of $67.88. * Given a 95% confidence interval critical value of t = 2.04, what is the upper bound (upper end) of a 95% confidence interval for the difference between two averages? Use (μloyalty program no loyalty program) for the order. Note: 1- Only round your final answer. Round your final answer to two decimal places.
Identify whether the studies described here are based on (1) single samples, (2) paired samples, or (3) independent samples. Cardiovascular disease risk factors are compared in husbands and wives. A nutritional exam is applied to a random sample of individuals. Results are compared to the results of the whole nation. An investigator compares vaccination histories in 30 autistic schoolchildren to a simple random sample of non-autistic children from the same school district.
We are interested in analysing the effect of the lockout laws introduced in some areas of the Sydney CBD and nearby surrounds on the number of alcohol-related violent incidents. Suppose we have two samples of data on the number of violent incidents in a number of local areas of the Sydney CBD and nearby surrounds. Pubs, hotels and clubs located in a subset of these areas became subject to the lockout laws when they were introduced in 2014. The first sample is from 2010 before the introduction of the lockout laws, and the second is from 2015 after the introduction of the law. The hypothesis we wish to test is that the introduction of the lockout laws reduces violent incidents in the areas in which the lockout laws were put in place. We use a difference-in-difference model on the pooled data from 2010 and 2015. We find the following results: viol_inc hat = 33.21 (5.29) + 12.43lockout (7.01) – 4.19Yr2015 (2.98) – 3.32 (lockout x Yr2015) (1.85) N = 181, R^2 = 0.128 Where: viol_incis the…
Researchers investigate how the presence of cell phones influence the quality of human interaction. Subjects are randomly selected from a population and divided into an experimental group that is asked to leave their phones in the front of the room and a control group that are not asked to leave their cell phones at the front of the room. Subjects are left alone for 10 minutes and then asked to take a survey designed to measure quality of interactions they had with others in the experiment. What statistical test is appropriate?
You are a sales manager for a grocery store, and you want to see if the introduction of a new sales promotion will increase the sales in your store. To do so, you decided to create an experiment by giving a small sample of customers the promotion before expanding it to a larger customer base. You gave 18 people the promotion, and also observed the sales of 27 people who did not get the promotion as a control group. You found those who received the promotion to have an average monthly sales of $456.60, with a sample standard deviation of $52.23. You found those who did not receive the promotion had an average monthly sales of $361.46, with a sample standard deviation of $56.11. Suppose you want to use hypothesis testing (two-sample test) to investigate if the promotion has increased the sales of your store. Using the order promotion no promotion in your hypothesis test, what is the value of the test statistic for your analysis? Note: 1- Only round your final answer. Round your final…
Explain if there was a statistically significant difference between the group means. did you arrive at your conclusion?
For several decades, it was a common practice in Southern California for houses to be built with pools in the backyard (as any airplane flight which ends at a Southern California airport will reveal). Now, however, that practice may be changing, possibly because of the recent demand for landscaped homes, which experts believe help reduce pollution. A recent study examined a random sample of 167 houses built in Southern California between 1950 and 1985 and an independent, random sample of 80 houses built in Southern California from 1992 to the present. The sample of houses built in 1950-1985 contained 71 houses with pools, and the sample of houses built from 1992-present contained 31 houses with pools. Based on this survey, can we conclude, at the 0.05 level of significance, that the proportion p1 of all Southern California houses built in 1950-1985 that were built with pools is greater than the proportion p2 of all Southern California houses built from…