research team conducts a survey to determine the area of land used for farming in Iowa. The team randomly selects house addresses and sends the survey by
... [Show More] mail.
Which type of sampling method is the research team using?
Systematic random sampling
Cluster sampling
Multi-stage sampling
Simple random sampling
RATIONALE
By choosing randomly from the house addresses all households should have an equal chance of being chosen. This would make it a simple random sample.
CONCEPT
Simple Random and Systematic Random Sampling
2
The following shows the Consumer Price Index (CPI) for the years 2000-2005. All of the values use a reference year of 1983.
Which of the following is true about the CPI, based on the information?
$100 in 1983 would be equivalent to $178 in 2001.
$100 in 2002 would have been worth $189.70 in 1983.
$100 in 2000 would be equivalent to $194.50 in 2005.
$100 in 2003 would be equivalent to $183.70 in 1983.
RATIONALE
Recall the CPI gives us a measure of price changes over time and allows us to transform values in one year to another. The value of the CPI in the base year is 100. This means that for $100 in 1983 is equivalent to $178 in 2001.
CONCEPT
Index Number and Reference Value
3
At a school of 900 students, 20% have blue eyes. A student randomly selects 100 students and finds 17% of them have blue eyes. A second student takes another random sample of 90 students and finds 24% of them have blue eyes.
Which of the following explains why there is a difference between the two percentages?
The samples were not random samples.
Random error; the numbers were different due to variability inherent in sampling.
Both samples suffered from non-response bias.
The sample sizes were both too small.
RATIONALE
When sampling, there is always some variability that occurs. So,
although the sample values are different and not equal to the true overall proportion of 20%, since they were randomly chosen, the differences are simply due to the variability that comes from sampling and not due to some systematic bias. As the sample size increases we would expect these differences to get smaller.
CONCEPT
Random and Systematic Errors
4
The traffic volumes at a major intersection in New York were surveyed every day between one and four in the afternoon for a month to study the traffic patterns in the city.
Which of the following types of bias affects the conclusions of the survey?
Selection bias
Non-response bias
Response bias
Deliberate bias
RATIONALE
Selection bias is when the mode of selection introduces a bias in the sample so that it is not representative of the population of interest. Since they only collected information from 1 to 4pm, this is a selection bias.
CONCEPT
Selection and Deliberate Bias
5
A scientist is conducting a study on the effect of eating chocolate and overall mood. They believe that gender is a significant factor. The participants are divided by gender. Then, within each group, participants are randomly assigned to consume either chocolate or a placebo and then rate their mood for the day. This experiment will run for two weeks.
Which type of experimental design does this situation describe?
Randomized Block Design
Completely Randomized Design
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Matched-Pair Design
RATIONALE
Since women are randomly assigned chocolate or placebo, this is a completely randomized design.
CONCEPT
Randomized Block Design
6
Which of these statements best defines a stratified random sample?
It is a sample where the population is first broken into groups and then elements are randomly selected, in proportion, from each group.
It is a sample where every nth element of the population is selected in a sequence.
It is a sample where the population is divided into roughly equal groups, and then elements are randomly selected from each group.
It is a sample in which every element has the same chance of being selected from the total population.
RATIONALE
Recall that a stratified random sample is first broken up into homogenous groups called strata. From those strata a random sample is then chosen.
CONCEPT
Stratified Random and Cluster Sampling
7
Select the correct statement regarding experiments.
A researcher can control the environment and observe the response.
A researcher cannot control the environment but can observe the response.
A researcher can control the environment but cannot observe the response.
A researcher [Show Less]