Quiz on Notes 3

Which of the following graphs represents a symmetric, bimodal distribution?

• A bell-shaped curve with one peak in the center

• A curve with two peaks that are mirror images on either side of the center

• A flat, uniform distribution

• A skewed distribution with one tail longer than the other

A unimodal, right skewed distribution has which of the following characteristics?

• A single peak with a longer tail on the right

• A single peak with a longer tail on the left

• Two peaks with a symmetric shape

• A flat, uniform distribution

What is an outlier in statistics?

• An outlier is an individual piece of data that falls outside the overall pattern of the distribution.

• An outlier is the average value of a data set.

• An outlier is the most frequently occurring value in a data set.

• An outlier is a value that is always within the range of the data set.

List the three rules for handling outliers in data:

• 1) Plot the data 2) Determine whether there is an outlier. If so, be sure that the data is accurate. 3) Determine if there is a valid reason that the outlier can be removed. If there isn’t, don’t remove it just identify it.

• 1) Remove all outliers immediately 2) Never check data accuracy 3) Ignore the reason for outliers.

• 1) Plot the data 2) Remove any data point that looks different 3) Do not document changes.

• 1) Only use statistical formulas 2) Always remove the highest and lowest values 3) Never question the data source.

There are three measures of center in statistics: ________, ________, and ________.

• Mean, Median, and Mode

• Mean, Range, and Variance

• Median, Mode, and Range

• Mode, Variance, and Standard Deviation

What is the formula for the mean of a sample?

• The mean of a sample is calculated as the sum of all observations divided by the number of observations: x̄ = (Σxi) / n

• The mean of a sample is calculated as the product of all observations: x̄ = (Πxi)

• The mean of a sample is calculated as the sum of all observations squared: x̄ = (Σxi^2) / n

• The mean of a sample is calculated as the sum of all observations divided by n-1: x̄ = (Σxi) / (n-1)

What is the mean number of siblings in our class?

• 2.45 siblings

• 1.75 siblings

• 3.10 siblings

• 0.95 siblings

Why do we not always use the mean to describe the center of a data set?

• Because the inclusion of outliers in a data set can affect the mean.

• Because the mean is always the largest value in the data set.

• Because the mean is always equal to the median.

• Because the mean ignores all data values except the maximum and minimum.

Match the following statistical terms with their definitions:

• number of observations

• each individual observation

• capital sigma = “add up”

• capital sigma = “add up”

• mean of a sample

• mean of a sample

• each individual observation

• number of observations

There is very clearly an outlier: the zero score. There might be legitimate reasons to eliminate the outlier. Why?

• Because it may be an error or not representative of the data.

• Because it is the highest value in the dataset.

• Because it improves the mean score.

• Because it is required by statistical law.