Lesson_02_Notes

# Lesson_02_Notes - Turning Data Into Information

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Turning Data Into Information Introduction Let's get started! Here is what you will learn in this lesson. Learning objectives for this lesson Upon completion of this lesson, you should be able to understand: the importance of graphing your data how to interpret the shape of a distribution what is a five-number summary and its interpretation the meaning of descriptive statistics what "average" means in statistics-speak the relationship between mean and median of a distribution some basic Minitab statistics and graphing methods Four features to consider for quantitative variables are: Shape 1. Center or Location 2. Spread (variability) 3. Outliers 4. hovertips What's a hovertip? A hovertip is a kind of "tooltip" that appears when the mouse rests above something. Displaying Distributions of Data with Graphs The distribution of a variable shows its pattern of variation, as given by the values of the variables and their frequencies. The following data set, SAT_DATA.XLS , or SAT_DATA.MTW (data from College Board) contains the mean SAT scores for each of the 50 US states and Washington D.C., as well the participation rates and geographic region of each state. The data patterns however are not yet clear. To get an idea of the pattern of variation of a categorical Turning Data Into Information http://onlinecourses.science.psu.edu/stat200/book/export/html/1 1 of 15 9/27/2010 11:44 PM

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variable such as region, we can display the information with a bar graph or pie chart . Using Minitab Using SPSS To create a piechart in Mintab: Open the data set SAT_DATA.MTW 1. From the menu bar select Graph > Pie Chart 2. Click inside the window under Categorical Variables. This will bring up the list of categorical variables in the data set. 3. From the list of variables click on Region and then click the Select button. This should place the variable Region in the Categorical Variables window. 4. Click OK 5. This should result in the following pie chart: In Minitab, if you place your mouse over any slice of the pie you will get the value of the overall percentage of the pie that region covers. For example, place your mouse over the blue colored slice (again this has to be done in Minitab not on the notes!) and you will see that for the Region MA (Mid Atlantic) 5.9% of the 50 states plus Washington D.C. fall into this category. Turning Data Into Information http://onlinecourses.science.psu.edu/stat200/book/export/html/1 2 of 15 9/27/2010 11:44 PM
To produce a bar graph or bar chart, return to the menu bar in Minitab and from the Graph options select Bar Chart then Simple. The steps will proceed similar from Step 3 above. In the Minitab Bar Chart, however, placing your mouse over a bar produces the number within that category. For example, if you place your mouse over the region labeled MA (again this has to be done in Minitab not on the notes!) you will see that three (3) of the 50 states plus Washington D.C. are classified as Mid Atlantic. Note that 3/51 equals the 5.9% from the pie chart:

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## Lesson_02_Notes - Turning Data Into Information

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