Not only is the older Gax somewhat unstable, but it also offers meaningful estimatesof fitting parameter uncertaintiesonlyfor the separate ‘linear regression’; custom modelshave no convenient way to get uncertainty estimates. Since fitting parameters are effectivelymeasurements that the computer has deduced from the data, it is essential that we be ableto specify the uncertainties and the units that must accompany them. These are the reasonswhy we prefer Ga3 that has a less obvious user interface.134

Appendix CUsing Microsoft ExcelC.1Creating plots and curve fitsHelpful TipThe primary advantage of Excel is that students have access to it at home. However,it is more challenging to perform statistical-based fits in Excel unless you write yourown spreadsheet or macros. It is recommended that you perform your data analysiswith Graphical Analysis 3.4 in the lab. However, you always have access to Excel inmany locations in case you want to plot outside the lab.This short list of resources will help guide you in creating figures in Excel, if you decideto use it.•A good introduction to basic graphing in Excel is provided by the LabWrite project:•Curve fitting in Excel can be performed, but sometimes it is much more painful thanusing a dedicated data analysis program.For least-squares curve fitting, this linkdetails how to use Excel:Neither do Excel’s least-squares fitting parameters come specified with uncertaintyestimates even after you go through these acrobatics.•We can use Excel’s “LINEST” function to provide complete statistics on straight lines.See ‘linest’ in Excel’s Help files to learn more about its usage.135

APPENDIX C: Using ExcelC.2Performing CalculationsAll calculations in spreadsheets begin with “=”. First, select the cell that will hold the resultof the calculation, type “=”, and enter the formula to be evaluated. Typing “=5+9” and‘Enter’ will yield “14” in the cell; the cell beneath will then be selected. If you need a cell tocontain ‘=’ instead the results of a calculation, precede it with a single quote ‘ ’. . . anythingyou type after that will be displayed verbatim. Even numeric characters won’t be numbersafter ‘ ’.If this was the extent of their capabilities, spreadsheets would not be very popular. Eachspreadsheet cell is at the intersection of a column having alphabetic label at the top and arow having numeric label at the left. ‘A1’ is the cell at the top left corner of the sheet, ‘C8’is at the eighth row and third column, and ‘Z26’ is at the26throw and the26thcolumn.After column ‘Z’ comes column ‘AA’ to ‘AZ’, ‘BA’ to ‘BZ’,. . . , ‘ZA’ to ‘ZZ’. If even morecolumns are needed, three, four, and five characters can be used. Column ‘numbers’ countup just like decimal digits, but column designations have base 26 instead of base 10.