Exam 1: Introduction to Statistics

Determine whether the given value is a discrete or continuous variable. People are asked to state how many times in the last month they visited their family doctor.

A gardener has 75 clients, 45% of whom are businesses. Find the number of business clients.

The good design of experiments includes blinding, ________, and ________.

A sample of 120 employees of a company is selected, and the average age is found to be 37 years.

The similarity between an ordinal level of measurement and an interval level of measurement is that ________.

Identify the type of observational study (cross-sectional, retrospective, prospective). -Explain what is meant by the term "confounding" and give an example of an experiment in which confounding is likely to be a problem.

Would an observational study or an experiment be more appropriate to investigate the effects on humans of a substance known to be toxic? Explain.

Identify the type of observational study (cross-sectional, retrospective, prospective). -In a clinical trial for a new headache medication, participants are randomly assigned to a treatment group or a placebo group. They do not know whether they are receiving the medication or a placebo. However the doctors administering the medication and evaluating the results do know which participants are receiving the medication. This experiment is blind but not double blind. Explain what this means and why the absence of double blinding could cause a problem.

Provide an appropriate response. -A psychology student wishes to investigate differences in political opinions between business majors and political science majors at her college. She randomly selects 100 students from the 260 business majors and 100 Students from the 180 political science majors. Does this sampling plan result in a random sample? Simple Random sample? Explain.

A marijuana survey included 1610 responses from a list of approximately 241,500,000 adults in the United States from which every 150,000th name was surveyed. Identify which of these types of sampling is used:

Identify which of these types of sampling is used: random, stratified, systematic, cluster, convenience. -A pollster uses a computer to generate 500 random numbers, then interviews the voters corresponding to those numbers.

A clinic gives a drug to a group of ten patients and a placebo to another group of ten patients to find out if the drug has an effect on the patients' illness.

A manufacturer of laptop computers claims that only 1% of their computers are defective. In a sample of 600 computers, it was found that 3% were defective. If the proportion of defectives were really only 1%, there would be less than 1 chance in 1000 of getting such a large proportion of defective laptops in the sample. Is there statistically significant evidence against the manufacturer's claim? Why or why not?

A psychology student wishes to investigate differences in political opinions between business majors and political science majors at her college. She randomly selects 100 students from the 260 business majors and 100 Students from the 180 political science majors. Does this sampling plan result in a random sample? Simple Random sample? Explain.

Determine which of the four levels of measurement is most appropriate. Students' grades of A, B, or C, on a test.