This preview shows pages 1–2. Sign up to view the full content.
Mean: Arithmetic average of the observations in a data set. (“average value”) Mean is the value
which balances the data.
Skewed distribution: A distribution is skewed to the right if the right side of the histogram
(containing the half of the observations with larger values) extends much farther out than the left
side. It is skewed to the left if the left side of the histogram extends much farther out than the
right side.
Mean is sensitive to the influence of a few extreme observations. These may be outliers, but a
skewed distribution that has no outliers will also pull the mean toward its long tail. Because the
mean cannot resist the influence of extreme observations, we say that it is not a resistant measure
of center. The median, unlike the mean, is resistant.
The median M is the midpoint of a distribution, the number such that half the observations are
smaller and the other half are larger. 9”typical value”) To find the median of a distribution:
1. Arrange all observations in order of size, from smallest to largest.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Winter '11
 PattiColling

Click to edit the document details