Statistics 220

This class covers the main concepts of statistics and relates these concepts to shop situations.

Class Details

Class Name:
Statistics 220
This class covers the main concepts of statistics and relates these concepts to shop situations.
Number of Lessons:
Additional Language:
Spanish, Chinese
Related 2.0 Class:
Statistics 231

Class Outline

  • Objectives
  • What Is Statistics?
  • What Is Variation?
  • Natural vs. Unnatural Variation
  • Why Use Statistics?
  • Probability and Sampling
  • Mean
  • Types of Mean
  • Median and Mode
  • The Histogram
  • The Bell-Shaped Curve
  • Types of Bell-Shaped Curves
  • Range
  • Standard Deviation
  • Standard Deviation and the Bell-Shaped Curve
  • Standard Deviation: An Example
  • Random Sampling
  • Summary


  • Define statistics.
  • Explain how variation appears in a shop.
  • Distinguish between natural and unnatural variation.
  • Describe common uses for statistics.
  • Define probability.
  • Calculate the mean for a set of numbers.
  • Distinguish between a population mean and sample mean.
  • Calculate the median for a set of numbers.
  • Calculate the mode for a set of numbers.
  • Describe the information contained in a histogram.
  • Describe the appearance of a bell-shaped curve.
  • Describe how the shape of a bell-shaped curve represents numerical data.
  • Explain the method for calculating the range.
  • Describe how standard deviation represents numerical data.
  • Describe how standard deviation appears on the bell-shaped curve.
  • Describe how standard deviation relates to probability.
  • Describe how random sampling generates numerical data.

Job Roles


  • CMfgT
  • MSSC Quality Practices and Measurement


Vocabulary Term Definition
bell-shaped curve A common type of histogram characterized by a high center, tapered sides, and bell-flared edges. A bell-shaped curve reflects conditions that exhibit natural variation.
data A collection of numbers or facts that is used as a basis for making conclusions.
fraction A numerical expression representing a part of a larger whole. A fraction can be converted to a decimal by dividing the upper number, or numerator, by the lower number, or denominator.
histogram A visual graph that shows the frequency of a range of variables.
horizontal scale The portion of a histogram that lists the range of variables.
mean The average of a numerical set. It is found by dividing the sum of a set of numbers by the number of members in the group.
median The value of a numerical set that equally divides the number of values that are larger and smaller. For example, in a set containing nine numbers, the median would be the fifth number.
mode The value of a numerical set that appears with the greatest frequency.
natural variation Variation resulting from sources that are normal and expected. Natural variation is predictable over time.
percentage A numerical expression that includes a percent sign, with 100 assumed as the denominator.
population mean The mean of a numerical set that includes all the numbers within the entire group.
probability The likelihood that a particular event will happen in the future. Probability can be expressed as a fraction, ratio, or percentage.
process A set of activities that uses resources to transform inputs into outputs. Essentially, a process describes the way "things get done."
random sampling The process of collecting and analyzing only a small representative portion of a larger group. Each item must have the same likelihood of being selected.
range The difference between the smallest and the largest values within a numerical set.
ratio A numerical expression representing a part of a larger whole or proportion. A ratio consists of two numbers separated by a colon.
sample mean A mean of a numerical set that includes an average of only a portion of the numbers within a group.
standard deviation A number representing the degree of variation within a numerical set.
statistics The science of collecting, summarizing, and analyzing numerical data. Statistics makes it possible to predict the likelihood of events.
unnatural variation Variation resulting from one or more sources that involve a fundamental change in a process. Unnatural variation is undesirable.
variation A difference between two or more similar things.
vertical scale The portion of a histogram that indicates the frequency of each variable.