hw.SLR.Initial.Excel - 12/3/2010 Simple Linear Regression:...

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Unformatted text preview: 12/3/2010 Simple Linear Regression: Initial Page 1 Linear Regression Homework Rev 12/03/10 Turn this in WHEN YOU ENTER CLASS, not at break or after class - even if you walk in late.. There are 3 things to staple, in this order, WITH CLASS NUMBER at the top right of each page: [1] answers to the questions (include your name) [2] the filled-in graph I provided (no other graph is acceptable) which you fill out by hand, not using Excel and [3] a printout (no PrtSc is needed) from the Excel program of your results. (For credit, the assignment pages must be stapled. If several assignments are turned in at the same time, each assignment is to be stapled, but the several different assignments are not stapled together.) NOTE: DF = n-1-1 = 8 . 1. First, make sure you have the Data Analysis add-in installed in Excel: go to Tools, Data Analysis. a. If you don't have it, look up in help for instructions on how to install this add-in. b. (You could also install the DataPro software add-in if your text has a CD, and follow the instructions in whatever text you have.) hw.SLR.Initial.Excel.doc Source: problem #11-7 (text: Data Analysis & Decision Making with Microsoft Excel Albright, Winston, Zappe 2nd Edition) For houses of a certain size, Y is the average utility bill for that month, and X is the average temperature for that month. Each record (row) has an average bill and the average temperature for that month. 1. Copy all 3 columns from the bottom of this document and paste into Excel, including the headings. (Or, just the 2 right-most columns, which are the only ones needed.) 2. Click on Tools, Data Analysis, Regression, OK 3. Make sure the cursor is in the box labeled "Input Y Range" and click on the worksheet and highlight the monthly bills including the heading. (We’ll ignore the column with months.) 4. Click in the box "Input X Range" and highlight the temperature column including the heading. 5. Click in the "Labels" box (meaning you are including the labels or headings with your data) 6. Click the radio button "Output Range" and then immediately click in the box to its right and then click somewhere on your worksheet, say A18 (and this is where Excel's output will go). Click OK. 7. Print out this Excel result (use landscape if needed) to be turned in, along with the (filled-in BY HAND ONLY USING STRAIGHT-EDGE) graph below and the answers to the questions (typed or written). No Excel graphs. 8. On the attached graph (this attached one MUST be used), plot the original data values, and draw the LS regression line. Show how you determined where the LS line should go. 9. Question: State the sample prediction line equation both in symbols and with numbers. 10. Question: What does this say about the relationship? What happens as temperature rises? Be specific. What does the regression line suggest? Look at the plotted data and give your assessment. 11. Question: Look at the p-values for the intercept and for the X variable. What do you conclude? Don't simply say "reject" or "not reject" - what do the p-values say about the variables and whether they are valid or should be in the model? (Keep in mind what the point of the slope hypothesis test is.) 12. Question: How good is the fit and how can you tell? (Not just looking at the graph.) 13. Question: Give the value of RSQUARE and the interpretation as specified in class. 14. Question: State the correlation, show how you got it, and give the interpretation (2 parts) as described in class. DATA ON NEXT PAGE 12/3/2010 Simple Linear Regression: Initial Page 2 Data: Average Monthly Utility Bills for Homes of a Certain Size Month AvgBill January $148.50 February $136.50 March $117.00 April $91.50 May $82.50 June $94.50 July $120.00 August $142.50 September $97.50 October $84.00 November $111.00 December $139.50 hw.SLR.initial.cdr AvgTemp 38 45 49 57 69 78 84 89 79 64 54 41 Y 150 140 130 120 110 100 90 80 ~~~~ ~~~~ 10 20 30 40 50 60 70 80 90 X USE RULER/STRAIGHT-EDGE FOR YOUR LS LINE ONLY THIS GRAPH may be used. A graph created by Excel is not acceptable. The assignment sheets must be stapled for credit. ...
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