x bar or p bar
Questions about probabilities or percentages require you to solve for p bar. Questions about _____ require you to solve for x bar.
means
A confidence interval reflects uncertainty due to using a ________ instead of the whole population.
Sample
If the p value is LESS than alpha, you should REJECT the __________ hypothesis.
Null
A Type I error occurs when we _______ the null hypothesis even though it is actually true.
reject
The probability of all possible outcomes in a sample space must sum to ________.
1 or 100%
In 2024, the Amazon Alexa app was downloaded 2800 times per day from the Google Play Store. Assume that the number of downloads per day from Google Play are normally distributed with a mean of 2800 and a standard deviation of 860.
What is the probability there are between 1500 and 2500 downloads a day?
Given this information, would you use the t table or the z table to solve this question?
z table
As the confidence level increases, the confidence interval becomes _______.
wider
H0: μ < 20
Ha: μ > 20
Is this a lower-tail or upper-tail test?
upper
A Type II error occurs when we fail to reject the null hypothesis even though it is actually _______.
false
A correlation coefficient indicates both the ________ and the direction of a relationship between two variables.
strength
Sales at a clothing chain are currently running at an annual rate of $310 per square foot. You have been asked by management to conduct a study of 27 locations. Assume the standard deviation in annual sales per square foot for the population of all 575 store locations is $76.
What is the expected value of x bar?
$310
A narrower confidence interval means _______ precision.
more or greater
True or False:
Changing the alpha level can change whether you reject the null hypothesis in favor of the alternative, even when the p-value stays the same.
TRUE
A Type I error is also known as a false _____.
positive
A confidence interval provides a range of values that is likely to contain the true ________.
population parameter
In a sample of 30 respondents to a questionnaire about school quality, 72 percent said they were "very satisfied" with their schools.
What is the standard error of this sample?
0.082 (hint: this is a p bar question, so use those equations)
A confidence interval is the sample mean plus and minus the __________.
margin of error
The null hypothesis represents the _____.
status quo/world as it is.
A Type II error is also known as a false _____.
negative
Expected value weights each possible outcome by its ________.
probability
Sales at a sunglasses chain are currently running at an annual rate of $222 per square foot. Assume the standard deviation in annual sales per square foot for the population of all 7 store locations is $11.
At what amount per square foot would you consider a store to be especially low-performing (an outlier)?
$189 or less (hint: you have to use a stand-in for the z score, and then solve for x).
You could get a smaller standard deviation (and therefore a narrower confidence interval) by increasing the __________.
sample size
The alternative hypothesis represents what the researcher is trying to _______.
support or test
A medical test is designed to detect a rare disease. The null hypothesis states that a patient does not have the disease. If the test incorrectly identifies a healthy patient as having the disease, this is a _______ error. If the test incorrectly indicates that a sick patient is healthy, this is a _______ error.
Type I; Type II
Statistics focuses on using information from a ________ to make conclusions about a larger ________.
sample; population