To figure the T-test using an Excel Spreadsheet, bring up Excel from the programs icons and do the following:
- Enter your 2 columns of data (control & experimental) into the spreadsheet cells in two columns. Label the columns according to the treatments you used (for example: Without Alcohol & With Alcohol)
- To do a T-test is simple using functions. Place your cursor in a cell below where your two columns are. Choose from the menu "Insert;" "Function;" "Statistical;" "TTest."
- For "Array 1" click the little spreadsheet icon over to the right of the space. This takes you back to your spreadsheet, so highlight the first data set of your controls. Hit enter.
- For "Array 2" click the little spreadsheet icon to the right of the space and highlight the data set of your experimentals. Hit enter.
- Type 2 in the "Tails" blank because you have two sets of data.
- Type 3 in the "Type" because this is probably a two samples with unequal variance. Hit enter.
- You now read the probability that your null hypothesis is correct (p). UNLESS YOU ARE GOING TO A SCIENCE COMPETITION WITH YOUR PROJECT, YOU CAN STOP HERE.
- To figure the t= value, you can click into the cell below the p value and choose "Insert;" "Function;" "Statistical;" "TINV;" & "OK."
- For "Probability" you click on the spreadsheet icon to the right and then click on the cell where your probability value is.
- For "Deg_Freedom" you click into the blank space and type the degrees freedom ((n1-1)+(n2-1)). Click "OK."