2. QM 2113 - Spring 2002 Statistics for Decision Making Excel for Statistics: An Overview

3. Student Objectives  Perform basic Excel tasks – Building formulae – Copy/paste – Insert rows/columns – Move – Modify displays  Use Excel functions for basic statistics – Descriptives: mean, median, standard deviation, quantiles – Integrate with presentation features  Summarize guidelines for spreadsheet design and development

4. First,...  Turn in your homework – Histograms – Bar charts – Quantiles for KIVZ – Old stuff (look at the roster) eMail address Questionnaire info  Monday: meet in BU 221

5. Here’s an Exercise  Goal: – Demonstrate Excel formulae and display concepts – Application to data analysis – But not a demo of Excel’s statistics capability  Given income values: $76,723 $37,452 $22,557 $60,155  Calculate average & standard deviation  Create attractive tabular display

6. Working the Exercise (Quick & Dirty)  Column A: type values (no $ or comma)  Use Excel’s  tool to sum values  Divide sum by n (use COUNT, not 4)  Column B: subtract x-bar (use absolute addressing) from first x value  Copy result down 3 cells  Column C: square first deviation and copy result down 3 cells  Sum squared deviations  Divide result by n-1  Take square root of the result

7. Working the Exercise (Cleaning it Up)  Insert four rows at top and 1 column at left  Create column headings  Center, boldface, and italicize column headings  Adjust column widths  Format raw data values as currency with 0 decimal places  Format intermediate calculations appropriately  Add appropriate labels for x-bar and s  Create an overall centered title for table

8. Now, Let’s Use Excel More Efficiently  KIVZ data: analysis of McCall incomes  Download dataset from the Web – Don’t open within browser – Instead, save to disk and then open in Excel  Enter data into Column A (type or copy from original worksheet)

9. Using Excel’s Built-In Functions  Summarize central tendency – Mean (AVERAGE) – Median (MEDIAN)  Summarize spread – Standard deviation (STDEV) – Range (MAX and MIN)  Calculate also – Percentiles – Cumulative frequency

10. Spreadsheet Guidelines  Save your work often (once per step)  Keep in mind that spreadsheets are typically reused – Updated data – Modified to fit similar situations – Use Data Analysis tool only as quick & dirty  Avoid using constants in formulae  Keep data separate from cells with calculations  Consider locking cells involving calculations  Do whatever it takes not to type data

11. Odds & Ends  Inference examples – Hypothesis testing – Estimation  Some notes on variation – What’s a “variance”? – The CV: answering the question “How much is much?” – Where is the variation? Median versus mean Skew Using the histogram to address this question  Discrepancies in quantile computations

12. Homework  Use Excel to calculate average income and standard deviation for Channel 6 as demonstrated in first exercise  Use Excel statistical functions to calculate descriptive statistics for overall McCall viewing time  More info to be posted at website