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Re: Experiments with large N
Huge samples are very nice if you can get 'em, though such is not always
the case, alas.
If I had a large (very large) N I would be more interested in have a
glance of the population distribution. And this is the reason why, I
think, large N studies are important.
For example, last year Semal and Demany (JASA, 2006) showed that there
are listerers that are able to detect subtle pitch differences but, at
the same time, are not able to tell the direction of these pitch
differences (up or down). They showed also that there are listeners that
do not show such a dissociation. How is the distribution of this trait
among the population? Are the first listeners a small or a relatively
large amount of the population?
Think about. Pitch perception is one of the most investigated topic in
auditory perception. Why do we discover this only in 2006? Is it because
the average study is run with few listeners only and these listeners
are, in the majority of cases, the "usual suspects" (e.g., authors,
people with a background of a minimum of 1000 hours of psycho-beeps
In textbooks we often read that JND for pitch is about 1%. After reading
Semal and Demany results I asked myself: is this figure real? Does it
reflect all the population? Which part of the population? For which
It is trivial to stress that, with large N, statistical power goes soon
very high. I think the goal of large N study is different: have, at
least once, a real glance of the population.
Massimo Grassi - PhD
Dipartimento di Psicologia Generale
Via Venezia 8 - 35131 Padova - Italy