Re: the midpoint

Devi Jankowicz (
Wed, 5 May 1999 23:42:47 +0000

Bob Green writes:

>Recently I was having an e-mail discussion regarding the midpoint, as often
>used in repertory grids. The midpoint can denote either a middle value or
>that the construct is not applicable (NA). These are different issues,
>though at times the midpoint is used as a catchall for both issues.
>As I understand it options include:
>a) forced choice/don't include a midpoint
>b) the midpoint is labelled, as a bit like both etc or a bit like neither
>or NA
>c) transform the scale into a unipolar scale, with 0 = NA etc
>d) treat NA as a missing value, though I'm not sure of grid programs that
>allow for this.
>I would be interested to hear other suggestions or preferences

which prompts me to offer two thoughts.

a) Mantz Yorke did a very interesting paper on this, and related issues,
at one of the early International PCP conferences, which was reprinted as
Yorke (1989). I remember that Jack Adams-Webber took issue with some of
Mantz' assertions, and I think that the paper concerned is Adams-Webber
(1989) though I could be wrong. Both are extremely thought-provoking and
exactly relate to the issues you have raised: and several related ones,
often disregarded in the "rush to quantify" that a grid induces.

b) One of the very elegant things about Mildred Shaw's / Brian Gaines'
REPGRID2 package is that it allows you to be a bit more discriminating
about quantifying a meaning which you would otherwise, under certain
circumstances, be forced to enter into the grid as a midpoint value. The
programme makes it possible for you to enter a response of "both ends of
the construct apply" and "neither of the ends of the construct apply",
and still permits cluster and principal components analysis.
Since I don't use a PC I have no idea if all the other grid packages
offer this facility; but it's certainly a very helpful one, and just
another reason for... (all together now, "groan").. Yes! for doing one's
computing on a Macintosh!

Kindest regards,

Devi Jankowicz

Adams-Webber, J. (1989) "Some reflections on the 'meaning' of repertory
grid responses"
_International Journal of Personal Construct Psychology_ 2, 1, 77-92.
Yorke, M. (1989) "The intolerable wrestle: words, numbers, and meanings"
_International Journal of Personal Construct Psychology_ 2, 1, 65-78.