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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: Probability distribution for a runs test of sequentially administered items |

Date |
Thu, 4 Mar 2010 22:48:19 -0000 |

I don't think the second has greater stigma or less charisma than the first. The problem has some similarities with that tackled by SJ-6-4 st0044_1 . . . . . . . . . . . . Software update for nruns and nrunsi (help nruns, nrunsi if installed) . . . . . . N. Smeeton and N. J. Cox Q4/06 SJ 6(4):597 introduces commands nruns and nrunsi for analyzing sequences stored in a variable or supplied on the fly SJ-3-3 st0044 Do-it-yourself shuffling & the number of runs under randomness . . . . . . . . . . . . . . . . . . . . . . . N. Smeeton and N. J. Cox Q3/03 SJ 3(3):270--277 (no commands) explains estimation of the probability of an event under randomness; illustrates a simple method of random shuffling; and shows derivation of conditional probability distribution of the number of runs so you might find that a useful start. Both paper and code are freely available. Nick n.j.cox@durham.ac.uk -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Barth Riley Sent: 04 March 2010 22:43 To: statalist@hsphsun2.harvard.edu Subject: st: Probability distribution for a runs test of sequentially administered items Dear Statalist I am exploring the possibility of using a Runs test to assess whether a set of sequentially administered item responses (i.e., as in a computerized adaptive test) is "in process" (with alternating correct/incorrect responses towards the end of the test) or out of process (reflecting aberrant responding, such as guessing or specialized knowledge). To do this, I would like to apply a probability distribution for the run length (number of consecutive pass/yes or fail/no responses) one would expect at a given point during the testing given that the respondent were answering the items as expected (in process). I was wondering if such a probability distribution already exists (and if so, what is it?) or if I would have to derive it via simulation. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: RE: RE: Probability distribution for a runs test of sequentially administered items***From:*"Barth Riley" <BarthRiley@comcast.net>

**References**:**st: Probability distribution for a runs test of sequentially administered items***From:*"Barth Riley" <BarthRiley@comcast.net>

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