Statistical Reasoning 2.1 Vocabulary Statistical Reasoning

Distribution What values the variable takes, and how often it takes these values. Use the center (median), spread, and describe the shape.

Median The midpoint of the distribution.

Spread The distance between the highest observation and the lowest observation.

Shape The overall pattern of a distribution.

Skewed Left Right The left side of the graph extends much farther out than the right side. The right side of the graph extends much further out than the left side.

Symmetric If the right, and left sides of the graph are approximate mirror images of each other.

Measures of Center The method of finding the mean, mode, median, spread, standard deviation, and range of a data set.

Mean The average of a set of observations.

Standard Deviation Measures the average distance of the observation from their mean.

VIDEO TIME Measures of Center Answer the questions on your handout!

Pie Chart A chart used to show proportion, can ONLY be used if percentages add up to 100%.

Bar Graph Graph of a frequency distribution for categorical data. Represented with vertical or horizontal bars whose area is proportional to the frequency, relative frequency or percent of that category. If the categorical variable is ordinal, the logical order of the categories should be preserved in the chart.

Dot Plot A graphical display that shows data where each point is represented by a dot, “x”, etc.

Stem and Leaf Plot Organizes quantitative data in order from smallest to largest. One column lists the leading digits of the observations (usually on the left) called the stem. Then, the other column (usually on the right) lists the trailing digits of observations called the leaves. Useful in conveying shape of relatively small data sets, and identifying outliers.

Scatter Plot Graphically displays bivariate quantitative data in which each observation (x, y) is plotted in the plane.

Box and Whisker Plot Graphically represents the five number summary. Can be modified by identifying outliers.

Interquartile Range Measures the range of the middle 50% of the data.

Outlier An individual observation that falls outside the overall pattern of the graph.

Histogram A common graph of the distribution of a quantitative variable.