Instrumental Analysis

Statistics Prelab

Instructions

Review the following documents and Appendix 1 in the text before beginning these exercises.

Note: Use the browser's back arrow to return to this page.

Adjust your browser window so that it occupies the right half of the computer screen. Go to Program Manager, start Microsoft Excel, and adjust the Excel window to occupy the left half of the computer screen. With the windows side-by-side you can read the instructions in the browser window and work in the Excel window. At times you will need Excel in full screen. The data on the browser screen can be highlighted with the mouse and copied into Excel using Copy and Paste in the Edit menu. (If you prefer you can use your favorite spreadsheet.)

Helpful hints:

The button makes the window full screen.
The button reduces the size of the window.
Adjust the window by dragging an edge or corner with the mouse.
ALT-Tab cycles between windows.
Save your file often!

Exercise 1

If you are unfamiliar with spreadsheets do the quick preview. From the Help menu select Quick Preview and click on the Getting Started button. Work through this tutorial and when it is done click on the Return to MS Excel button. (The Quick Preview will occupy the full screen until it finishes.)

Exercise 2

Label the first sheet as Title and type CHEM 4114 - Statistics Lab and your name and date. Label the second sheet as Exercise 2 and copy the following data (Data Set 1) onto the sheet.

Data Set 1

Voltage (v)
0.453
0.444
0.457
0.448
0.451
0.495
0.447

Enter formulas to find the average and standard deviation of the data.

Click here to see an example screen.

Exercise 3

Label the third sheet as Exercise 3 and make a plot of Data Set 1.

Exercise 4

Label the fourth sheet as Exercise 4. Cut and paste the data and formulas from Exercise 2 onto sheet 4.

The sixth measurement in the data set is much higher than the other data. Show a Q-test calculation to determine if this data point can be rejected.

(Hint: the sixth data point can be discarded.) Delete the outlier and revise you formulas if necessary to recalculate the average and standard deviation. If you have to do extensive revision of your formulas, you may want to think about a more flexible way to write the formulas.

Exercise 5

Label the fifth sheet as Exercise 5 and cut and paste the following data (Data Set 2) onto the sheet.

Data Set 2

Concentration (ppb)	Analytical Signal 
0.00			0.002
5.00			0.259
10.00			0.489
25.00			1.284
50.00			2.407
100.00			4.903

Make a plot of Data Set 2. Do a linear regression to find the slope and intercept of the best line that fits this data. Report the standard deviations with these results.

Final Exercise

Print your worksheets, including the formulas, and tape them into your lab book. Save the worksheet to disk so you can use the formulas in calculations for your later labs.

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