Lessons 1 and 2: Turning Data Into
Information
Introduction
This lesson discusses the importance of "getting a picture" of your data and some of
the basics in interpreting these pictures.
Let's get started! Here is what you will learn in this lesson.
Learning objectives for this lesson
Upon completion of this lesson, you should be able to understand:
•
the importance of graphing your data
•
how to interpret the shape of a distribution
•
what is a fivenumber summary and its interpretation
•
the meaning of descriptive statistics
•
what "average" means in statisticsspeak
•
the relationship between mean and median of a distribution
•
some basic Minitab statistics and graphing methods
Four features to consider for quantitative variables are:
1.
Shape
2.
Location (center or average)
3.
Spread (variability)
4.
Outliers
Shape
The shape of a dataset is usually described as either
symmetric
, meaning that it is
similar on both sides of the center, or
skewed
, meaning that the values are more
spread out on one side of the center than on the other. If it is
skewed to the right (or
positivey skewed)
, the higher values (toward the right on a number line) are more
spread out than the lower values. If it is
skewed to the left (or negatively skewed)
,
the lower values (toward the left on a number line) are more spread out than the
higher values. A symmetric dataset may be
bellshaped
or another symmetric shape.
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 Spring '08
 BARROSO,JOAOR
 Statistics, Standard Deviation

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