Chapter 3: Basic Statistical Concepts
Brief Summary
Statistics! Just this one ten letter word by itself tends to instill more fear and anxiety in undergraduate
and graduate students than any other word we know. We have learned from our experience as college
professors that when we say we are going to cover statistics in our assessment courses, responses from
students will be:
▪ Can we take this course Pass/Fail?
▪ What is the latest date to drop the course?
▪ I hate math-I always get confused!
▪ Do we really have to know this? If so how come?
The fact is, whether your students are avid fans of statistics or generally do not enjoy it, you have to
teach statistics when you are teaching a course in special education assessment. Statistics play a vital
role in the understanding of disability awareness. Although there are numerous reasons for students
know statistics, of primary importance to special educators is that without a proper understanding of it,
you can’t interpret test results.
When working with large sets of data it is important that they be organized in a fashion that makes some
sense to the reader. In special education, this done through methods known as descriptive statistics.
Descriptive statistics summarize and describe data. In this chapter, we will discuss basic descriptive
statistics used every day in special education. By the end of this chapter, your students should
understand (and in some cases be able to calculate) the following:
▪ Scales of measurement
▪ Frequency distributions
▪ Measures of central tendency (mean, median and mode)
▪ Range
▪ Variance
▪ Standard deviation
▪ The normal curve
▪ Skewed distributions
▪ Correlations
Lecture and Discussion Outline
I. Overview Of Statistics
II. Scales of Measurement
III. Measures of Central Tendency
A. Mean
1. Calculation of the Mean
2. Statistical model problems
B. Median
1. Calculation of the Median
2. Statistical model problems
C. Mode
1. Calculation of the Mean
2. Statistical model problems
IV. Frequency Distribution
A. Creating a frequency distribution
B. Model problems
V. Range
A. Calculation of the range
B. Statistical model problems
VI. Variance
A. Calculation of the Variance
B. Statistical model problems
VII. Standard Deviation
A. Calculation of Standard Deviation:
B. Normal Curve
C. Statistical model problems
VIII. Skewed Distributions
A. Positively skewed distribution
B. Negatively skewed distribution
IX. Correlations
A. Types of correlations
B. Correlations range from +1.00 to -1.00.
C. Correlations do not indicate cause and effect
D. Practice problem
X. Conclusion
Essay Questions
▪ Explain the importance of knowing statistics as a special educator. If you didn’t understand
statistics, what are some problems you might encounter as a special educator?
▪ What are the four types of scales of measurement? Define each and give an example.