Math 1 · Unit 12 · Lesson 3 · part 1 of 4
The Words We Use
The vocabulary for this lesson, in one place.
Words we use
| Word | Plain English | What you do |
|---|---|---|
| Spread (variability) | How far apart the values are. | Two sets with the same center can differ here. |
| Range | Maximum minus minimum. | Quick, but one extreme value can make it huge. |
| Quartiles, Q1 and Q3 | The values a quarter and three quarters of the way through the ordered data. | The median of each half, leaving out the overall median when n is odd. |
| Interquartile range, IQR | Q3 minus Q1: the spread of the middle half, the width of the box. | Resists extreme values, like the median. |
| Mean absolute deviation | The average distance from the mean, from 7th grade. | Drop the signs, then average. |
| Standard deviation | A typical distance from the mean: square the distances, average, square root. | Bigger means more spread out; 0 means all the same. |
| σ and s | Sigma, the population standard deviation (divide by n); s, the sample version (divide by n − 1). | Everyone: σ. A sample: s. |