Exam 1: Introduction to Statistics

Determine whether the given description corresponds to an experiment or an observational study. A stock analyst selects a stock from a group of twenty for investment by choosing the stock with the greatest earnings per share reported for the last quarter.

A tax auditor selects every 1000th income tax return that is received. Identify which of these types of sampling is used.

Identify which type of sampling is used. numbers, then interviews the voters corresponding to those numbers.

In a cross-sectional study, data are _____________

Determine whether the given value is from a discrete or continuous data set. The time it takes a computer to complete a task.

Which of the following is an inappropriate way to deal with missing data?

Identify which type of sampling is used. The name of each contestant is written on a separate card, the cards are placed in a bag, and three names are picked from the bag.

Identify the type of study used. A town obtains current employment data by polling 10,000 of its citizens this month.

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

Identify the type of observational study used. A town obtains current employment data by polling 10,000 of its citizens this month.

Distinguish between categorical and quantitative data. Give an example of each

Form a conclusion about statistical significance. Do not make any formal calculations. Either use the results provided or make subjective judgments about the results. Last year, the average math SAT score for students at one school was 475. The headmaster introduced new teaching methods hoping to improve scores. This year, the mean math SAT score for a sample of students was 481. Is there statistically significant evidence that the new teaching method is effective? If the teaching method had no effect, there would be roughly a 3 in 10 chance of seeing such an increase. Does the result have statistical significance? Why or why not? Does the result have practical significance?

Use critical thinking to develop an alternative conclusion. A study shows that the number of reported sexually transmitted diseases was significantly higher for high schools that offered courses in sex education than for high schools that did not. Conclusion: The introduction of sex education courses at the high school level has resulted in increased promiscuity among teens.

"38% of adults in the United States regularly visit a doctor". This conclusion was reached by a college student after she had questioned 520 randomly selected members of her college. What is wrong with her conclusion?

A management survey for a company surveyed 235 employees. 44.7% of the employees surveyed were females. The number of males would be ___________________.

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

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.

Would an observational study or an experiment be more appropriate to investigate the effects on fertilizer on plant growth? Explain.

An education expert is researching teaching methods and wishes to interview teachers from a particular school district. She randomly selects ten schools from the district and interviews all of the teachers at the selected schools. Does this sampling plan result in a random sample? Simple random sample? Explain.

What type of data values are quantitative and the number of values is finite or countable?