E-15 within item analysis

[cblatt]

When running an item analysis for a quiz, 3 questions had Point biseral greater than 1 (1.09, 3.56, -3.56, -5.97), and the number is followed by E-15.  What does this mean?

[kblack · Accepted solution]

Hi  @cblatt  Welcome to the Canvas Community. That is the format that most spreadsheet software--including Excel--will use for scientific notation.  You can read more about it here: Display numbers in scientific (exponential) notation - Excel 

1.09E-15 (to use one of your examples) is really .00000000000000109 .  Basically, you start with 1.09 and move the decimal 15 places to the left when the number is negative.  In fact, you can likely see the actual number (in Excel, at least) by clicking in that cell and looking up at the formula bar.  Otherwise, you can convert it to a "normal-looking" number by clicking in the cell, selecting Number as the number format, and then clicking the increase decimal button enough times until you see the full number.

I hope this helps a bit, Claire.