AP Statistics : Data

Study concepts, example questions & explanations for AP Statistics

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Example Questions

Example Question #1 :How To Find The Least Squares Regression Line

In a regression analysis, the y-variable should be the ___________ variable, and the x-variable should be the ___________ variable.

Possible Answers:

First, Second

Qualified, Unqualified

Independent, Dependent

Dependent, Independent

Greater, Lesser

Correct answer:

Dependent, Independent

Explanation:

回归测试试图侦破ermine one variable's ability to predict another variable. In this analysis, one variable is dependent (the one predicted), and the other is independent (the variable that predicts). Therefore, the dependent variable is the y-variable and the independent variable is the x-variable.

Example Question #2 :How To Find The Least Squares Regression Line

If a data set has a perfect negative linear correlation, has a slope ofand an explanatory variable standard deviation of, what is the standard deviation of the response variable?

Possible Answers:

Correct answer:

Explanation:

The key here is to utilize

.

"Perfect negative linear correlation" means, while the rest of the problem indicatesand. This enables us to solve for.



Example Question #3 :How To Find The Least Squares Regression Line

A least-squares regression line has equationand a correlation of. It is also known that. What is

Possible Answers:

Correct answer:

Explanation:

Use the formula.

Plug in the given values forandand this becomes an algebra problem.

Example Question #1 :How To Find Outliers

Use the following five number summary to determine if there are any outliers in the data set:

Minimum:

Q1:

Median:

Q3:

Maximum:

Possible Answers:

There is at least one outlier on the low end of the distribution and no outliers on the high end of the distribution.

There are no outliers.

There is at least one outlier on the high end of the distribution and at least one outlier on the low end of the distribution.

There is at least one outlier on the high end of the distribution and no outliers on the low end of the distribution.

It is not possible to determine if there are outliers based on the information given.

Correct answer:

There are no outliers.

Explanation:

An observation is an outlier if it falls more thanabove the upper quartile or more thanbelow the lower quartile.

. The minimum value isso there are no outliers in the low end of the distribution.

. The maximum value isso there are no outliers in the high end of the distribution.

Example Question #2 :How To Find Outliers

For a data set, the first quartile is第三四分位数and the median is.

Based on this information, a new observation can be considered an outlier if it is greater than what?

Possible Answers:

Correct answer:

Explanation:

Use thecriteria:

This states that anything less thanor greater thanwill be an outlier.

Thus, we want to find

where.

Therefore, any new observation greater than 115 can be considered an outlier.

Example Question #3 :How To Find Outliers

You are given the following information regarding a particular data set:

Q1:

Q3:

Assume that the numbersandare in the data set. How many of these numbers are outliers?

Possible Answers:

One

None of the numbers are outliers

Two

Four

Three

Correct answer:

Two

Explanation:

In order to find the outliers, we can use theandformulas.

Only two numbers are outside of the calculated range and therefore are outliers:and.

Example Question #4 :How To Find Outliers

Use the following five number summary to answer the question below:

Min:

Q1:

Med:

Q3:

Max:

Which of the following is true regarding outliers?

Possible Answers:

There are no outliers in the lower side of the data set, but there is at least one outlier on the upper side of the data set.

There are no outliers in this data set.

There are no outliers in the upper side of the data set, but there is at least one outlier on the lower side of the data set.

There is only one outlier in this entire data set.

至少有一个离群值低的一面the data set and at least one outlier in the upper side of the data set.

Correct answer:

至少有一个离群值低的一面the data set and at least one outlier in the upper side of the data set.

Explanation:

Using theandformulas, we can determine that both the minimum and maximum values of the data set are outliers.

This allows us to determine that there isat leastone outlier in the upper side of the data set andat leastone outlier in the lower side of the data set. Without any more information, we are not able to determine the exact number of outliers in the entire data set.

Example Question #5 :How To Find Outliers

Which values in the above data set are outliers?

Possible Answers:

no outliers

Correct answer:

Explanation:

Step 1: Recall the definition of an outlier as any value in a data set that is greater thanor less than.

Step 2: Calculate the IQR, which is the third quartile minus the first quartile, or. To findand, first write the data in ascending order.

. Then, find the median, which is. Next, Find the median of data below, which is. Do the same for the data aboveto get. By finding the medians of the lower and upper halves of the data, you are able to find the value,that is greater than 25% of the data and, the value greater than 75% of the data.

Step 3:. No values less than 64.

. In the data set, 105 > 104, so it is an outlier.

Example Question #6 :How To Find Outliers

A certain distribution has a 1st quartile of 8 and a 3rd quartile of 16. Which of the following data points would be considered an outlier?

Possible Answers:

Correct answer:

Explanation:

An outlier is any data point that fallsabove the 3rd quartile and below the first quartile. The inter-quartile range isand. The lower bound would beand the upper bound would be. The only possible answer outside of this range is.

Example Question #1 :How To Create Residual Plots

On a residual plot, the-axis displays the __________ and the-axis displays__________.

Possible Answers:

independent variable; the dependent variable

independent variable;

dependent variable; residuals

residuals; the independent variable

residuals; theresiduals

Correct answer:

independent variable;

Explanation:

A residual plot shows the difference between the actual and expected value, or residual. This goes on the y-axis. The plot shows these residuals in relation to the independent variable.

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