Transcript Analyzing Data

Why do we analyze data?
 It is important to analyze data because you need to
determine the extent to which the hypothesized
relationship does or does not exist.
 You need to find both the central tendency and the
variance within the data.
Qualitative vs Quantitative
Data
 First, you need to determine if your data is qualitative
or quantitative.
 Qualitative data is based on observations and
descriptions, for example color or texture
 Quantitative data deals with numbers and data that can
be measured, for example length, weight, or speed
 SO, is your data qualitative or quantitative?
Central Tendency
 Central tendency is the central, or typical, value to a set of
data.
 You can measure central tendency in many ways:
 Mean- the arithmetic average of a set of data, can be
calculated by dividing the sum of the elements by the number
of elements, is strongly influenced by extreme values
 Median- the middle element in a set of data once the data has
been ordered by magnitude, not influenced by one or two
extreme values
 Mode- the most frequent data value
Variance
 Variance measures how far a set of numbers are spread out.
A small variance indicates that the numbers are close to the
mean while a large variance indicates that the numbers are
spread out from each other.
 Measures of Variation
 Range – the difference between the greatest and least values in
the set
 Frequency distribution – depicts the number of cases falling
into each category, used in qualitative data
 Standard Deviation – measures how closely the individual
points cluster around the mean
What Do I Choose??
 Choose your numerical summaries based on this table:
Type of Data
Central Tendency
Variation
Quantitative
Mean
Range
Standard Deviation
Qualitative
Mode
Frequency Distribution
Graphs
 You need to choose the graph that best represents your data.
 Types of Graphs:
 Bar Graph – common way to show categorical data with a
non-standard scale ( quantitative data)
 Line Graph – used for continuous data with a standard scale
to show the change in a variable over time
 Scatter Plot – used when two measurements are made for
each element in the sample, helps to determine if two
characteristics are correlated
WHAT Do I Graph?
 You should be able to graph both the central tendency
and the variation in the data.
 Raw data (all the trails) is generally not shown in graph
form.
 X-axis indicated independent variable while the y-axis
indicates the dependent variable
Discussion of Data/
Data Analysis
 You will need to describe your data in paragraph form,
mainly answering the question “What does the data tell
me?”
 Follow these steps for your discussion of data:
1.
2.
3.
4.
Write a topic sentence stating the independent and dependent
variables, and a reference to graphs and tables
Write a sentence describing the correlation between variables
if one exists.
Write sentences comparing the measures of central tendencies
of the groups.
Write sentences describing the variation within the groups.