STAT 210 1st EditionLECTURE 5Outline of Last LectureI. Design of ExperimentsII. Treatment GroupsOutline of Current LectureIII. Descriptive StatisticsIV. Graphical proceduresV. Stem and leaf plotCurrent LectureVI. Descriptive Statistics describes 4 thingsa. Center of the distributionb. Spread of the distributionc. Shape of the distributiond. Any unusual features in the distributionVII. Purpose of Graphical proceduresa. Simplify datab. Make easy to describe distributionsc. Make it easy to make statistical inferenceVIII. Qualitativea. Bar graphb. Pie chartIX. Quantitativea. Divided into class interestb. Each measurement should fall in one and exactly one intervalX. Stem and Leaf Plot (can be used to sort large list of data)a. Can graphically display distributionb. Determine center of distributionc. Shape of distributiond. Determine any unusual featuresi. Any range of values not representedii. Concentration of dataiii. Any outliersXI. Steps of Stem and Leaf Plota. If necessary, modify numbers so they have the same amount of digits (if range is from 15-4063, 15 becomes 0015, 273 becomes 0273, etc.)b. Divide each data set into two parts (first is stem, other is leaf. [ex. If number is 95, 9 is stem, 5 is leaf])c. Determine possible stem values and list vertically from smallest to largestd. State a defining rulei. Ex. 9 Ι 5 = 95 as opposed to 9 Ι 5 = 9.5ii. A person should be able to look at this and put it back togethere. Order stems from smallest to largest (optional but recommended) XII. Standard Stem and Leaf Plota. Can be used with 3, 4, 5 etc. digit numbersb. Between 10-15 stems is idealXIII. Advantages of Stem and Leaf Plota. Display the distribution of the datab. Can be used to determine the center, spread, shape, and any unusual features of the distributionc. Retain the actual datad. Easy to constructe. Make sorting of the data easierXIV. Disadvantagesa. Not very effective for large data sets (would take a long time to construct).b. Choice of the stems depends on the data type and data range. Different choices for the stems can cause different looking
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