Was this an experiment or an observational​ study?

The income of residents of Chicago, IL has a bell shaped and symmetric histogram, with a mean of $65,000 and a S.D. of $13,000.  1) What percentage of residents have an income more than $78,000 or less than $52,000?   2) what percentage of residents have an income between $39,000 and $91,000?   3) What percentage of residents have an income less than $104,000?  4) What percentage have an income more than $65000?  5)  Less than $26,000 Hint: you need to draw a curve for each part 1-4, and calculate the mean ± 1, 2, 3 S.D.

A warehouse manager wants to know if there is an association between the shift worked and being on time for work. To investigate, he selects a random sample of 70 workers and classifies each one according to the shift they worked most recently and whether they were on time for work. He was unable to classify a substantial number of people as being on time, so he classified those individuals as unknown. The data are displayed in the table.   The manager would like to know if these data provide convincing evidence of an association between the shift worked and being on time in the large population of all workers at this warehouse. The random and 10% conditions are met. Is the Large Counts condition met? Yes, the smallest expected count is 5, so all expected counts are at least 5. Yes, the smallest expected count is 8.54, so all expected counts are at least 5. No, the smallest expected count is 2.56, so the expected counts are not all at least 5. No, the smallest expected count is…

Researchers asked parents of 19 American children, ages 8 to 12, to complete surveys on the number of hours their children spent reading and the number of hours they spent on screen-based media time. Each of the children also underwent magnetic resonance imaging (MRI) to assess connectivity in the brain. More time spent reading was associated with higher connectivity, while more screen time was associated with lower connectivity in the brains of the children. 1. What is the sample in this study? c 2. What is a possible population? F6 3. Is this an experiment or an observational study? Why did you make that decision? 4. Can we conclude that more time spent reading increases connectivity in children's brains? 5. Identify a possible confounding variable and explain how it meets the definition of a confounding variable. MacBook Air tv♫ F7 * 2 DII F8 ( ZA F9 1 F10 & F11 DOCX A

1. To determine whether using a cell phone while driving increases the risk of an accident, a researcher examines accident reports to obtain data about the number of accidents in which a driver was talking on a cell phone. A. Is this a randomized experiment or an observational study? B. Assume that the accident reports show that people were more likely to have an accident while talking on a cell phone. Could this result be due to confounding?

In an article that appears on a website,† Carlton Gunn, a public defender in Seattle, Washington, wrote about how he uses statistics in his work as an attorney. He states the following. I personally have used statistics in trying to challenge the reliability of drug testing results. Suppose the chance of a mistake in the taking and processing of a urine sample for a drug test is just 1 in 100. And your client has a "dirty" (i.e., positive) test result. Only a 1 in 100 chance that it could be wrong? Not necessarily. If the vast majority of all tests given—say 99 in 100—are truly clean, then you get one false dirty and one true dirty in every 100 tests, so that half of the dirty tests are false. Define the following events as given below. TD = event that the test result is dirty TC = event that the test result is clean D = event that the person tested is actually dirty C = event that the person tested is actually clean (a) Using the information in the quote, compute the following…

A random sample of employees participating in a company fitness program were asked how many days they logged an exercise activity in the past month. Their responses are reported in the histogram below.Based on the histogram above, what is the class width? Clas width = ? Days What is the sample size? Sample size = ? employees

A De Anza student decided to determine whether the percent of men who participate in sports at De Anza College is higher than the percent of women who participate in sports at De Anza College. Out of 67 women, 12 said they participate in sports. 13 of the 45 men surveyed said they participate in sports. a. ) What are the type I and type II errors? Explain them in the context of this problem.b. ) Describe the sample statistics in words. What is the distribution of the sample statistic? Explain why you used this distribution.Can someone please help me make sense of these questions?

A study tested the effects of 4 different dosages of a new antidepressant on reducing depressive symptoms in one group of depressed participants. The order of the four dosages was counterbalanced across participants. Which statistical test should be used? Select one: a. One-way between subjects ANOVA b. One-way repeated measures ANOVA c. Two-way between subjects ANOVA Incorrect d. None of these options

The National Football League (NFL) is conducting a survey of fan behavior by collecting a random sample of 240 NFL fans. One question asks fans if they have ever participated in a violent act in or around their favorite team's stadium. Nationally, 28% of NFL fans have participated in a violent act around their team’s stadium. The research finds that 14% of Green Bay Packers fans have committed a violent act on game day. Conduct a significance test to answer the research question: Is there a significant difference (a=.05) in the proportion of Green Bay Packers fans compared to the rest of the NFL fans that have participated in a violent act?  What is the obtained score? What is the P-Value?