HISTOGRAMS Frequency Tables too

Histograms A special type of bar graph in which the bars touch Width of bar has meaning (age range, distance interval, time period…) Data is grouped into classes Especially useful with LARGE amounts of data Overall shape assists us in recognizing patterns Deviations from the norm??

Histograms continued Exact/ specific data is hidden 21 year olds who watch Space Voyage=? How choose # of classes (bars)? Impt to ask self: “would info be hidden/lost?” “will nothing stand out?” Usually 5-10… I like 7 Often textbook will tell you. W= ? Begin with the smallest data value, then step by the width

Frequency Tables Basically columns to help organize raw data before graphically displaying them Has classes/groups; tally marks; frequency number; class midpoints or class marks (sometimes); relative frequency First class begins with the smallest number Next class starts with smallest + w Hungry Hippo?

Types of Histograms Normal (Symmetric) Rectangular Bimodal Skewed Right Skewed Left

Analysis When you are “done” with your graph, you are not finished! Center Shape Spread Outliers From histograms, dot plots, stem-leaf plots onward…