5 Questions for Facebook - Statistics.com: Data Science, Analytics & Statistics Courses

This question is about a drug study to compare two treatments for reducing blood pressure. A suitable group of patients is recruited and randomly divided into two groups, each group receiving one of the drugs. At the end of the study period you make the graphs of the reduction in blood pressure. The y-axis shows reduction in blood pressure. Based on the graph, which group had the greatest reduction in blood pressure?

Group 0

Group 1

Too close to call

Not enough information to tell

Economists reviewing certain income data determine that it is not Normally-distributed, so they decide to standardize it and convert it to z-scores. As a result,

The z-scores are now Normally-distributed

The z-scores, and comparison to a Normal distribution, can be used to determine what portion of the population falls into various income brackets.

Both of the above

None of the above

The marketing department at a mobile device manufacturer wants to gauge whether consumers would favor a device with larger dimensions. A proposal from a market research firm calls for surveying 1000 consumers, identifying sources of names and criteria for random selection, and contacting them by telephone, if needed for a response. The marketing manager points out that a much larger survey could be conducted much more cheaply simply using a popup on existing customer devices. Which of the following is true?

The smaller sample is likely to have less bias than the popup survey, but the greater size of the popup survey will correct for this effect.

A much more accurate answer could be obtained with the larger sample, but only if it exceeds 1000 by at least one standard deviation.

The smaller sample is likely to be more accurate, since it is more likely to avoid bias.

The smaller sample is likely to be more accurate, due to the higher standard deviation for the data it is measuring.

A politician running for office after a scandal wants to learn his favorability ratings. He can afford a sample survey of 200 voters, from which he would calculate x= "number in survey who regard him favorably" which would then be converted to a "percent favorable" estimate. Which of the following might be used after the survey to assess how much uncertainty there is in the resulting estimate, due to random chance?

A box with 100 slips of paper, x of them marked “favorable” and the remainder “not favorable”

A box with x slips of paper marked “favorable” and 200-x marked “not favorable.”

Random draws of x slips of paper from a box

Random draws of 200-x slips of paper from a box

A research firm has just completed an opinion survey using a sample of 250 voters in Menlo Park CA (pop. 33,000). Now they plan to do the same survey in Palo Alto CA (pop 66,000). How many voters should they sample in Palo Alto to achieve about the same degree of accuracy as in Menlo Park?

250

350

500

660

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