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I would like to point out that in my first message to BIOMCH-L
about "Standard terminology: NORMALIZED", I defined questionable the
nonlinear transformation which is defined as "NORMALIZATION" in the
book by Glass and Hopkins (Statistical methods in Education and Psychology),
and not other kinds of nonlinear transformations which are used in
statistics to correct skewed distributions of data.
The latter transformations (simply defined by Glass & Hopkins
as "TRANSFORMATIONS" -see p.70- or "NONLINEAR TRANSFORMATIONS" -see
note, p.70) are changes of scale, for example replacement of scores
by the logarithm or square root of the raw scores themselves, WHICH
MAKE THE FREQUENCY DISTRIBUTION MORE NEARLY NORMAL.
And that's perfectly acceptable to me. What I defined qiestionable
(and I am sure many will agree) is the normalization defined as in my
"Definition B" (see previous message), that MAKES THE DISTRIBUTION
PERFECTLY NORMAL (P E R F E C T L Y). Glass and Hopkins explain that:
"NORMALIZED scores are obtained by first converting the original scores to
percentiles and then converting each percentile to the score corresponding to
that percentile in a normal distribution"...
If you are curious to know why I think the latter kind of
statistical normalization is questionable, read my summary of responses
to my previous posting ("Standard terminology: NORMALIZED"). I will
post the summary tomorrow.
With regards,
Paolo de Leva
Istituto Superiore di Educazione Fisica
Biomechanics Lab
Via di Villa Pepoli, 4
00153 ROME
ITALY
Tel: 39-6-575.40.81
FAX: 39-6-361.30.65
e-mail address: DELEVA@RISCcics.ing.uniRoma1.IT
about "Standard terminology: NORMALIZED", I defined questionable the
nonlinear transformation which is defined as "NORMALIZATION" in the
book by Glass and Hopkins (Statistical methods in Education and Psychology),
and not other kinds of nonlinear transformations which are used in
statistics to correct skewed distributions of data.
The latter transformations (simply defined by Glass & Hopkins
as "TRANSFORMATIONS" -see p.70- or "NONLINEAR TRANSFORMATIONS" -see
note, p.70) are changes of scale, for example replacement of scores
by the logarithm or square root of the raw scores themselves, WHICH
MAKE THE FREQUENCY DISTRIBUTION MORE NEARLY NORMAL.
And that's perfectly acceptable to me. What I defined qiestionable
(and I am sure many will agree) is the normalization defined as in my
"Definition B" (see previous message), that MAKES THE DISTRIBUTION
PERFECTLY NORMAL (P E R F E C T L Y). Glass and Hopkins explain that:
"NORMALIZED scores are obtained by first converting the original scores to
percentiles and then converting each percentile to the score corresponding to
that percentile in a normal distribution"...
If you are curious to know why I think the latter kind of
statistical normalization is questionable, read my summary of responses
to my previous posting ("Standard terminology: NORMALIZED"). I will
post the summary tomorrow.
With regards,
Paolo de Leva
Istituto Superiore di Educazione Fisica
Biomechanics Lab
Via di Villa Pepoli, 4
00153 ROME
ITALY
Tel: 39-6-575.40.81
FAX: 39-6-361.30.65
e-mail address: DELEVA@RISCcics.ing.uniRoma1.IT