# Step 2 Unit 6 Key Terms

• Box-and-Whisker Plot– A diagram that summarizes data using the median, the upper and lowers quartiles, and the extreme values (minimum and maximum). Box and whisker plots are also known as box plots. It is constructed from the five-number summary of the data: Minimum, Q1 (lower quartile), Q2 (median), Q3 (upper quartile), Maximum.
• Frequency– The number of times an item, number, or event occurs in a set of data.
• Grouped Frequency Table– The organization of raw data in table form with classes and frequencies
• Histogram– A way of displaying numeric data using horizontal or vertical bars so that the height or length of the bars indicates frequency.
• Inter-Quartile Range (IQR)- The difference between the first and third quartiles. (Note that the first quartile and third quartiles are sometimes called upper and lower quartiles.)
• Interval– Separates a scale into equal parts.
• Maximum value– The largest value in a set of data.
• Mean Absolute Deviation– The average distance of each data value from the mean. The MAD is a gauge of “on average” how different the data values are from the mean value.
• Mean- The “average” or “fair share” value for the data. The mean is also the balance point of the corresponding data distribution. To find the mean, add all the data points together and divide by the total number of data points.
• Measures of Center– The mean and the median are both ways to measure the center for a set of data.
• Measures of Spread– The range and the Mean Absolute Deviation are both common ways to measure the spread for a set of data.
• Median– The value for which half the numbers are larger and half are smaller. If there are two middle numbers, the median is the arithmetic mean of the two middle numbers. Note: The median is a good choice to represent the center of a distribution when the distribution is skewed or outliers are present.
• Minimum value– The smallest value in a set of data.
• Mode– The number that occurs the most often in a list. There can be more than one mode or no mode.
• Outlier– A value that is very far away from most of the values in a data set.
• Range– A measure of spread for a set of data. To find the range, subtract the smallest value from the largest value in a set of data.
• Scale– Includes all of the numbers in the data. For example- using numbers 6, 9, 15, 20 would all be a part of the scale 6-20
• Stem-and-Leaf Plot– A graphical method used to represent ordered numerical data. Once the data are ordered, the stem and leaves are determined. Typically the stem is all but the last digit of each data point and the leaf is that last digit.