--> The most up-to-date data on time trials is maintained here.



The information below is presented only for historical reasons.  These days (year 2018), a laptop running a 7th or 8th generation i5 or i7 processor would take less than a minute to process the examples tabled below.


The data minuted in the secs-y table below were obtained in October 2003, on a Pentium 4 running at 2 GHz. N is the number of data records in the Data worksheet; Nits is the number of items to be scored; Item scores indicates the amount of time to produce IStats' matrix of item scores; No eigens indicates the total time to completion, that is, time to create the item scores, the matrix of Pearson correlations, the matrix of tetrachoric correlations, and the DAT worksheet; With eigens indicates how much longer the job took when eigenvalues were also computed.




Item scores

No eigens

With eigens



13 secs.

27 secs.

51 secs.



24 secs.

33 secs.

42 secs.



48 secs.

1:02 mins.

1:11 mins.



1:45 mins.

2:12 mins.

2:21 mins.



4:04 mins.

4:51 mins.

5:08 mins.


Note December 2004: we received a trial data set from a Lertap user with N=267 and Nits=150.  It took Lertap a total of 14 minutes to produce its IStats report for this data set (!) -- of this, 11 minutes were required to extract eigenvalues from the correlation matrix.  This test used the same computer mentioned above, a Pentium 4 running at 2 GHz.  At the end of 2004, this Pentium would be considered as being quite dated (it was new in early 2002); if you're wanting IStats reports for data sets with large Nits, hopefully you'll have a more powerful computer to work on.


Note July 2010: fresh tests with another data set. This one had N=4,700 and Nits=77.  In this case, it took Lertap 3 minutes to produce its IStats report, a figure which includes the 43 seconds required to extract eigenvalues from the correlation matrix. We used Excel 2010 for this, running on a Macintosh MacBook Pro (2.53 GHz; 4 GB RAM) with Parallels and Windows 7 (if you have a more conventional Windows computer, not a Mac, you'd likely observe better figures).


Note December 2012: for a comparison of Excel 2010 and Excel 2013 running times, you might have a look at this document with a few selected time trials.