Describing+Distributions+Numerically

Center: Finding the Median
The middle value that divides a histogram into two sections of equal areas is the **median**.

Spread: Home one the Range
When describing a distribution, you have to support the spread along the center. Measures of spread are **range**--the difference between the maximum and minimium values--and the **Interquartile Range,** the difference between the upper and lower quartile.


 * Key Concepts:**
 * **Center:** The median or the mode, depending on the symmetry of the graph. (If asymmetric, use the median; if symmetric, use the mean or the median.)
 * **Median:** When you organize the data, the middle number is the median. If there are two middle numbers, average them.
 * **Spread:** Basically how much area the graph covers. It can be tightly packed or spread out across the whole graph.
 * **Range:** maximum value - the minimum value
 * **Quartile:** the data split up into four sections to show the distribution of the majority of the data
 * **Interquartile Range (IQR):** Q3-Q1
 * **Percentile:** The percentage of values in a distribution that fall below a certain value.
 * **Five-Number Summary:** The minimum, the maximum, the quartiles (Q1 and Q3), and the median.
 * **Boxplot:** form of graphing data showing the five number summary
 * **Mean:** The mean is found by summing all the data values and dividing by the count.
 * **Variance:** The variances is the sum of squared deviations from the mean, divided by the count minus one.
 * **Standard Deviation:** The standard deviation is the square root of the variance.
 * **Comparing Distributions:**
 * **Comparing Boxplots:**