VOCD

Thu Aug 20 17:54:28 UTC 2015

A colleague and I found VOCD to correlate with standardized vocabulary profiles much better than TTR did:

Silverman, S (Now Stacy Wagovich). and Ratner, N. (2002). Measuring lexical diversity in children who stutter: application of vocd. Journal of Fluency Disorders, 27 (4), 1-16.

In our ongoing work, with adults who stutter, multiple aspects of expressive language use differ from that seen in typically fluent speakers; TTR does not reveal anything, but our adults who stutter speak much less. VOCD is showing statistical differences between the groups. Amanda is right, VOCD is impacted by sample size, but not as much. It will be interesting to see how MATTR compares, especially for use with child language or smaller samples. Has anyone out there tried it for child samples?

It will be interesting to try to derive ‘norms” for VOCD, since it is essentially an estimate, and you won’t get EXACTLY the same value twice. In fact, that’s how I know if my students are doing their own CLAN assignments ☺

N

Nan Bernstein Ratner, Fellow, ASHA; Fellow, AAAS
Board Certified Specialist-Child Language
Professor
Department of Hearing and Speech Sciences
University of Maryland
0100 Lefrak Hall
College Park, MD 20742
301-405-4217, 301-314-2023 (fax)
nratner at umd.edu<mailto:nratner at umd.edu>

http://hesp.umd.edu/facultyprofile/Bernstein%20Ratner/Nan

Director, University of Maryland Autism Research Consortium (UMARC)
Participating Faculty, Neuroscience and Cognitive Science (NACS)
Research Faculty, Maryland Language Science Center
Participating Faculty, Developmental Science

From: chibolts at googlegroups.com [mailto:chibolts at googlegroups.com] On Behalf Of Amanda Owen Van Horne
Sent: Thursday, August 20, 2015 9:31 AM
To: chibolts <chibolts at googlegroups.com>
Subject: Re: VOCD manual

Also see

Owen, A. J., & Leonard, L. B. (2002). Lexical Diversity in the Spontaneous Speech of Children With Specific Language ImpairmentApplication of D.Journal of Speech, Language, and Hearing Research, 45(5), 927-937.
Bottom line is that VOCD is better than TTR, but less transparent.  It does still vary with sample size, but to a lesser degree.

McCarthy, P. M., & Jarvis, S. (2010). MTLD, vocd-D, and HD-D: A validation study of sophisticated approaches to lexical diversity assessment. Behavior research methods, 42(2), 381-392.
Compares various methods of computing D.  Recommends  a variety of measures.

Koizumi, R. (2012). Relationships between text length and lexical diversity measures: can we use short texts of less than 100 tokens. Vocabulary Learning and Instruction, 1(1), 60-69.
Recommends MLTD

On Wednesday, August 19, 2015 at 9:46:58 AM UTC-5, Amber wrote:
In fact, perhaps I should just post my question on here. The CHAT manual talks about calculating D and states that it can be done on samples as small as 50 tokens. However, reliability is less good for small samples. Could anyone advise me on whether VOCD is still a more valid measure than TTR, even for small transcripts (e.g., during a shared-book reading session)? I assume that as long as the sample is large enough for KIDEVAL to be able to give me VOCD values then it is OK?
Thanks
Amber

On Wednesday, 19 August 2015 15:36:05 UTC+1, Amber wrote:
Dear all

The CLAN manual contains the following link, which no longer appears to work.

http://childes.psy.cmu.edu/manuals/vocd.doc

Is there a new link to the VOCD manual/another similar article?

Many thanks
Amber
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