Which of the following is the explanatory variable in this study?
Which of the following is a confounding variable in this study?
A magazine printed a survey in its monthly issue and asked readers to fill it out and send it
in. Over 1000 readers did so. This type of sample is called
Answer: a self-selected sample
Which one of the following variables is not categorical?
Which of the following would indicate that a dataset is not bell-shaped?
Answer: The mean is much smaller than the median
The value of a correlation is reported by a researcher to be r = −0.5. Which of the following statements is correct?
Answer: The x-variable explains 25% of the variability in the y-variable
Among people with age over 30, what's the "risk" of always exceeding the speed limit?
What is the approximate shape of the distribution?
Answer: Skewed to the right
Which of the following is not a way that we could use central tendency?
Answer: determine how accurately we can guess the value of an individual observation in our sample
If we had a population of values and took many possible samples of some size (n) from that population, calculated the mean of each of these samples, and then took the standard deviation of these sample means, we would have:
Answer: calculated the standard error of the mean
A human resources manager is interested to know if the mean number of sick days taken per year differs between three specific job titles within a company. What test should the manager use to examine this question?
Answer: one-factor analysis of variance (ANOVA)
A baker is interested in whether there is a difference in the mean ‘deliciousness’ ratings that customers give to a low-sugar option of a cookie and to a high-sugar option of a cookie, and whether the difference in mean rating for the low- and high-sugar options depends on the age group of the customer (child vs. adult). What test should the baker use to examine this question?
Answer: two-factor analysis of variance (ANOVA)
A polling company finds that 60% of Democrats give a ‘favorable’ rating for a senator and 52% of Republicans give a ‘favorable’ rating for the same senator. What should the company use if they want to know if this is a ‘statistically significant’ finding?
Answer: z-test for a difference in two proportions
A confidence interval describes what set of values?
For which scenario below would simulation be useful?
A pharmaceutical company is investigating a new drug (Drug A) as a potential replacement for an old drug (Drug B). They make several statements. Which of these statements most relates to the effect size of Drug A vs. Drug B.
Answer: on average, we would need to give 10 people Drug A to have one more survival than if we had given those 10 people Drug B
In the same scenario as above, which of the statements most relates to whether we can determine that the relationship between drug and survival rate is a cause-and-effect relationship?
Answer: the patients in the study were aged 20 – 40 with early-stage disease progression and were randomly assigned by the experimenter to take one of two drugs
Which is a question that we can answer directly with hypothesis testing?
Answer: what is the probability of observing our sample data by random chance, if some assumptions are true about the population?
In hypothesis testing, we use a to make an inference about a .
Answer: sample statistic; population parameter
Two dog owners are interested in whether their (shared) dog tends to run to a specific one of them first when they come home together. They walk through the door at the same time and record which person the dog runs to first. They repeat this procedure many times. What test should they use to ask if the dog runs to one of them more often than we would expect if the dog was choosing randomly between the owners?
Answer: binomial test for a single proportion