Section 2.3 Pictures of Data Statistics Section 2.3 Pictures of Data

Histograms A histogram is a bar graph in which the horizontal (x) axis represents the classes and the vertical (y) axis represents the frequency of each class. Bars are adjacent to each other (no gaps) and the first bar connects to the y-axis.

Relative frequency histogram – same shape and horizontal (x) axis as a histogram but the vertical (y) axis is marked with relative frequencies (percents) instead of actual frequencies.

Dotplot – a graph in which each data value is plotted as a point or a dot along a scale of values. Dots that represent the same values are stacked.

Stem-and-leaf plot – represents data by separating each value into two parts: the stem (typically the tens digit) and the leaf (the ones digit). Stems and leafs are both listed in order from least to greatest.

Advantages of stem-and-leaf: Can see distribution of the data. It’s a histogram turned on its side! Can still reconstruct the original data if needed. Can find the mean, median, and mode.

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