On Jan 13, 2015 3:37 PM, "Thomas Levine" <_@thomaslevine.com> wrote:

I have excerpted some relevant sections of McClelland & Ward, 1982.

First, the study supports the suggestion of longer seats.

> The apertures of the nonstandard seats used in this study were 0.07m
> longer than the currently recommended aperture. Longer apertures were
> clearly an improvement over recommended ones in terms of access.
> This confirms the suggestion made as a result of the previous
> anthropometric survey that a longer aperture would be more
> appropriate for toilet use. An enlarged seat aperture incorporated
> into future standards for the design of toilet seats would
> necessitate a longer bowl aperture than currently recommended.
> If the bowl aperture were not extended to be coincident with the seat,
> then at some point the rim would come within the aperture of the seat,
> and soiling of the bowl might result.
>
> Two consequences would result from the to the most negative responses.
> adoption of a longer seat aperture as standard, and these would be of
> great importance for the design of toilet sanitary ware and the
> related facilities. First, a longer aperture would require a major
> reappraisal of existing toilet designs by the sanitary-ware industry;
> this undoubtedly would involve considerable development and expense.
> The second consequence involves water economy. If a longer aperture
> were adopted, then the internal surface area of the bowl would
> probably increase or at least change in profile. This raises the
> question as to whether the demand that toilet bowls be flushed
> effectively with less water is compatible with a longer aperture.
> This paper is not the appropriate platform for a lengthy discussion
> of these topics, but if a new standard for toilet bowls is to be
> established that satisfies ergonomic criteria, then it is clear from
> this study that the question of the aperture length for both toilet
> seat and bowl needs to be resolved. In the authors' view, this would
> only be possible if a further study were undertaken, which would be
> based on the evaluation of fully operational toilet units.

Secondarily, the results suggest that people, especially women,
prefer seats that support the buttocks and thighs well.

> Given the similarities of seated positions adopted by men and women,
> the differences in preference may be due to the well-known anatomical
> differences that exist between men and women with respect to the
> pelvic region, in particular the differences in bi-ischial diameter
> and the distribution of flesh around the buttocks and thighs. These
> differences may require different emphasis on the support provided by
> toilet seats. However, as already noted, in terms of the psychometric
> scales used, both Seat 3, for men, and Seat 4, for women, were
> acceptable. Thus, given the constraint of selecting one seat type for
> both men and women, the results suggest that improvements in seat
> comfort may be obtained by providing greater support for both buttocks
> and thighs.

Finally, nobody had brought up the height of the seats, but I have to
mention their findings on this matter

> It is clear that the most significant difference in height
> requirement is between men and women. The overall seat heights
> derived from this study (HI) were, for men, a mean of 0.43m,
> standard deviation 0.030 m, and for women, mean 0.40 m, standard
> deviation 0.033 m. Accepting the premise that only one type of toilet
> bowl and seat can be considered for general use by adults, a toilet
> seat height of 0.4 m is recommended for the U.K. adult population.
> This height is, of course, based on the preference of unshod
> subjects. To take account of "average" indoor shoe heel heights,
> a value of, say, 0.050 m could be added, giving a figure of 0.450 m
> for seat height. This would be 0.020 m higher than the seat height of
> 0.430 m calculated to be the current British standard. The adoption
> of a seat at this height (0.450 m) would, however, militate against
> its suitability for the shorter members of the population, for
> example, small women wearing low-heeled footwear. The preferred
> height (Table 2) of the 2.5th percentile unshod female subjects was
> 0.338 m. A seat height of 0.450 m would thus be 0.112 m greater than
> that preferred by them and would, in fact, accord with the height
> preferences for only the 50th percentile female wearing heels of at
> least 5 em. A seat height of 0.450 m would be 0.030 m lower than the
> preferred overall height of 50th percentile male subjects if 0.050m
> is added for "average" shoe heel height (Table 2); it would be 0.050m
> higher than the preferred height of the 2.5th percentile male subject
> unshod. Because of the considerable body of opinion, already referred
> to, on the advantages of the squat rather than the seated posture,
> particularly for defecation, seat height favoring a comfortable
> seated posture for the smaller members of the population and a more
> squat posture for taller people, is to be preferred to one that was
> too high for smaller individuals in the seated posture. It is
> therefore suggested that a seat height of 0.40 m (the mean height for
> women, unshod) would be better than 0.45m as a fixed height to
> accommodate the adult population; 0.40 m would also be closer to the
> needs of the young than would 0.45 m. This height is approximately
> 0.03m lower than the height of a toilet seat set on a toilet bowl
> both of which conform to the current British standards (British
> Standards Institution, 1971, I977a, 1977b).

Tom

On 13 Jan 11:38, Jehan Tremback wrote:
> Definately plastic
>
> On Tue, Jan 13, 2015 at 11:37 AM, Patrik D'haeseleer <patrikd@gmail.com>
> wrote:
>
> > On Tue, Jan 13, 2015 at 11:12 AM, Thomas Levine <_@thomaslevine.com>
> > wrote:
> >
> >>
> >> I think new seats would also create a sense of maintenance/neatness that
> >> would encourage people to be neat themselves. Also, if we do get new
> >> seats,
> >> we might consider the findings of Ian McClelland and Joan Ward regarding
> >> the toilet seat preferences of different sexes.
> >>
> >> Ian L. McClelland and Joan S. Ward (1982). The Ergonomics of Toilet Seats.
> >>   Human Factors, 24(6): 713—725.
> >>
> >> That paper is proprietary, unfortunately, but I can recount it for anyone
> >> who is interested.
> >>
> >
> > Please do! Any recommendations regarding open vs closed front, wood vs
> > plastic?
> >
> > Patrik
> >
> >
> > _______________________________________________
> > sudo-discuss mailing list
> > sudo-discuss@lists.sudoroom.org
> > https://lists.sudoroom.org/listinfo/sudo-discuss
> >
> >

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