Basic Data Analysis: Descriptive Statistics

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Basic Data Analysis Descriptive Statistics

• Dr. John T. Drea
• Professor of Marketing
• Western Illinois University

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Coding and Data Entry

• Data Code Book (coding sheet)
• This is a copy of your survey which contains
  instructions on how to code each question
• -This is done to achieve consistency

Becomes this
This
Are you Male Female How satisfied are you
with our product? ___Very Satisfied ___Somewhat
Satisfied ___Somewhat Dissatisfied ___Very
Dissatisfied ___No opinion
Are you (1) Male (2) Female How satisfied
are you with our product? _1__Very
Satisfied _2__Somewhat Satisfied _3__Somewhat
Dissatisfied _4__Very Dissatisfied _5__No opinion
Write it down, make sure everyone coding has the
exact same sheet!
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Five types of statistical analysis
Descriptive
What are the characteristics of the respondents?
Inferential
What are the characteristics of the population?
Differences
Are two or more groups the same or different?
Associative
Are two or more variables related in a systematic
way?
Predictive
Can we predict one variable if we know one or
more other variables?
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Descriptive Analysis Measures of Central Tendency

• Mean the average (interval/ratio data)
• Median half of the responses fall above this
  point, half fall below this point (ordinal data)
• Mode the number that occurs most often in a
  string (nominal data)

Examine the following list What is the mean,
median and mode? 3
4 6 6 7 16 21
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Other Key Concepts in Descriptive Statistics

• Frequency the number of times a value is present
• Range the highest value minus the lowest value
• Std. Deviation the degree of variation in the
  responses
• Measure of skewness indicates the shape of the
  distribution ( right tail, - left tail)

Not skewed
Right skewed ()
Left skewed (-)
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Other Key Concepts in Descriptive Statistics

• Kurtosis how peaked a distribution is. A zero
  indicates normal distribution, positive numbers
  indicate a peak, negative numbers indicate a
  flatter distribution)

How does kurtosis relate to the standard
deviation?
Peaked distribution ()
Flat distribution (-)
Thanks, Scott!