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📚 Statistics with Technology 2e
Chapters ▾
1 Statistical Basics2 Graphical Descriptions of Data3 Examining the Evidence Using Graphs and Statistics4 Probability5 Discrete Probability Distributions6 Continuous Probability Distributions7 One-Sample Inference8 Estimation9 Two-Sample Inference10 Regression and Correlation11 Chi-Square and ANOVA Tests12 Appendix: Critical Value Tables

Chapter 3: Examining the Evidence Using Graphs and Statistics

This section focuses on measures of central tendency. Many times you are asking what to expect on average. Such as when you pick a major, you would probably ask how much you expect to earn in that field. If you are thinking of relocating to a new town, you might ask how much you can expect to pay for housing. If you are planting vegetables in the spring, you might want to know how long it will be until you can harvest. These questions, and many more, can be answered by knowing the center of the data set. There are three measures of the “center” of the data. They are the mode, median, and mean. Any of the values can be referred to as the “average.”

  • The mode is the data value that occurs the most frequently in the data. To find it, you count how often each data value occurs, and then determine which data value occurs most often.
  • The median is the data value in the middle of a sorted list of data. To find it, you put the data in order, and then determine which data value is in the middle of the data set.
  • The mean is the arithmetic average of the numbers. This is the center that most people call the average, though all three – mean, median, and mode – really are averages.

There are no symbols for the mode and the median, but the mean is used a great deal, and statisticians gave it a symbol. There are actually two symbols, one for the population parameter and one for the sample statistic. In most cases you cannot find the population parameter, so you use the sample statistic to estimate the population parameter.