STA 210 Test 1
If the variance of a set of data is computed to be 4, then the standard deviation is:
2
A recent poll of 1500 college-age students found that 885 agreed with U.S. foreign policy toward Israel. What is the corresponding 95% confidence interval (choose closest answer)?
59% plus or minus 3%
What is a simple random sample?
A sample chosen in such a way that all samples of that same size have the same chance of being chosen.
Which of the following are examples of strategies for reducing non-sampling errors? Use of technology-assisted confidential interview techniques Use of inducements for non-responders All of those listed here Awareness of psychology of question order
All those listed here
What is a cross-sectional sample?
An attempt to match the sample characteristics exactly to those of the population.
What is a non-sampling error?
An error caused by something other than the fact that a sample was selected instead of the entire population
Consider the following survey question: "The Mac operating system rarely gets infected by viruses and therefore Department of Education should only purchase Mac computers. Please answer Yes or No". What is one objection to this question, as asked?
Because of the "rarely gets infected by viruses" clause this question is a leading question.
A survey was conducted by Playboy, asking questions about the sex lives of 5,000 U.S. University and College students. One question asked: "Are you in a nude picture on someone's camera phone?" 34 percent said "yes". Name at least one error you'd expect this survey to suffer from even if all 15.9 million College and University students in the U.S. had answered, and not just 5,000.
Error caused by fabricated responses
Recall Harris Poll disclaimer mentioned in the Read All About It (or the video). Harris is a major polling organization that refuses to accompany their poll reports with a margin of error. What is one reason that was given for such a bold omission?
Harris recognizes that there are many sources of error that are not addressed by the MOE, so reporting it might be misleading.
What does the word "parameter" refer to in statistical science?
Number that describes the population
In the MOE Doesn't Apply Read All About It (or video), what was the issue with the question "Have you often, sometimes, hardly ever, or never felt bad because you were unfaithful to your wife?"
Of the 85% who said they "never felt bad about it" surely a large part of those had never been unfaithful to their wives. But the way the question was asked this wasn't an option for an answer.
What do we mean by "human inference?"
Off-hand phrase taken to mean inference we make from statistical constructs.
What kind of error does the margin of error address?
Random sampling error
Which of the following statements is true?
The mean and standard deviation are sensitive to outliers
What are the two keys to having confidence in your parameter estimate?
The probabilistic nature of the sample selection, and some neat mathematics that follow from this.
What is sampling variability?
The variability seen in statistics from sample to sample
What is "response substitution?"
This is the tendency for survey respondents to present their answers in a way that allows them to express their opinions about other issues that aren't the topic of the survey
What is the goal of sampling?
To make inferences about a population from what we know about our sample.
Which of the following is a strategy for reducing non-sampling errors?
Use of incentives for non-responders
Suppose you have a data set with 1000 observations in it. 500 of those are all 5 and 500 are 15. Then the standard deviation is about?
about 5
A Ph.D. candidate in the College of Education once defended her misleading and confusing questionnaire by arguing that her margin of error was low, only about 3%. This argument is:
confused, because the margin of error has nothing to do with biased questionnaire designs
Which of the following sources of error is addressed by the margin of error?
errors that comes from choosing a sample and not the entire population
What can one say about the sampling distribution of a sample statistic based on a simple random sample?
it is about bell-shaped and peaks above the parameter
A 1996 Gallup poll of eligible New Hampshire primary voters reported that "of 1200 voters surveyed, 24% would vote for Senator Bob Dole if the primary election were held today". The Gallup organization also reported that the margin of error for a sample of 1200 people is 3 percentage points. If the Gallup organization had wanted to make a confidence statement based on the same data, only with more confidence that the interval had captured the parameter, what do you think would happen to the margin of error? It would be
larger than 3%
You ask a question to a random sample of 1500 adults in Texas (population 18 million people) and to a separate random sample of 500 adults in Indiana (population 5.7 million people). You make separate 95% confidence statements about the percent of all adults in each state who agree. Your margin of error for Indiana is
larger than in Texas, because there are fewer people in the Indiana sample.
You ask a question to a random sample of 1000 adults in Texas (population 18 million people) and to a separate random sample of 1000 adults in Indiana (population 5.7 million people). You make separate 95% confidence statements about the percent of all adults in each state who agree. Your margin of error for Indiana is
the same as in Texas, because the two samples are the same size.
