**Dr. Kang Lee's Development Lab**

**Signal Detection Theory**

**Click here for ready-made Excel Work Sheet for SDT calculations.**

**Different experimental designs may require different formulas for calculating sensitivity and response bias measures. See Macmillan & Creelman (1991) for details.**

The following is an example of how to use Excel to compute the measures with data collected using a yes-no paradigm.**For d prime:**Put your hit and false alarm rate data into an Excel spreadsheet. Lets say the hit rates are in column A and the false alarm rates are in column B. In cell C1, define the function

**For beta (natural log):**Go to cell D1 and use this formula:

=-C1*0.5*(NORMSINV(A1)+(NORMSINV(B1)))where C1 refers to the d' value that is computed in that cell. Then copy and paste down column D so it will do all the rest of the beta calculations.

**For beta (ratio):**Go to cell E1 and use this formula:

= exp (D1)

For criterion c:

=-.5*(NORMSINV(A1) and NORMSINV(B1))

For normalized c’:

=-.5*(NORMSINV(A1) and NORMSINV(B1))/d’

**How to deal with hit rate of 1 and false alarm rate of 0:**If you have any hit rates of 1.0 or false alarm rates of 0, you need to do a standard correction on those first. There is some controversy about the best way to correct hit and false alarm rates, but the "standard" method is the one described below: