[BlindRUG] Measures of modality: understanding distribution shapes

Godfrey, Jonathan A.J.Godfrey at massey.ac.nz
Thu Jul 30 09:22:52 UTC 2015


Thanks,

With respect to the scatter plots: Take a look at WhereXY() before you code up the same idea. <smiles> It isn't possible to make this function part of the VI() as we can't get a scatter plot to have a defined class like is done for histograms etc.

Some discussions have already taken place on sonification. If you're interested in this idea, you might find another person on this list would appreciate the interaction, and might contact you off-list. We've tired the sonification of a histogram but it's not easy to work with. I think it is more likely to succeed on a density curve.

Thanks for the link. I'll take a peek.

Cheers,
Jonathan


From: BlindRUG [mailto:blindrug-bounces at nfbnet.org] On Behalf Of Gjalt-Jorn Peters via BlindRUG
Sent: Thursday, 30 July 2015 9:15 p.m.
To: Blind R Users Group
Cc: Gjalt-Jorn Peters
Subject: Re: [BlindRUG] Measures of modality: understanding distribution shapes

Dear Jonathan,

Thank you for your swift reply! VI sounds great - I had encountered BrailleR, but I'd missed this. It seems amazing, thank you!

It doesn't provide one convenient number, but it does enable blind people to explore their data in a similar way to 'sighted' (?) people. This is great!

Maybe I'll have time to write a method for scatterplots, e.g. generating an X by X grid and describing the number of datapoints in each grid cell in a table form? That would be faster without doing it from a scatterplot, I guess. Anyway, if I get around to it, I'll send it around to the list!

The sonification option also seems very interesting! Apparently, packages exist to let R produce sounds . . . This seems promising: http://www.inside-r.org/packages/cran/sound/docs/play - maybe also worth exploring later on :-)

Again, thank you very much, kind regards,

Gjalt-Jorn

Gjalt-Jorn Peters | http://behaviorchange.eu

Behavior change research | Health psychology
Intervention development | Applied social psychology

[

[GG]<http://greatergood.eu>

[OU]<http://ou.nl>

[UM]<http://maastrichtuniversity.nl>

}


On 2015-07-30 9:57, Godfrey, Jonathan via BlindRUG wrote:

Hi,



This is a great question.



Personally, I would be hoping the sample size is sufficient to allow me to increase the number of bins in a histogram to convince myself that the presence of bimodality is real. I can get the information from the VI() command on the histogram creation command. For example:

VI(hist(x))



I'm still trying to find a way of conveying a density curve to a blind audience. It's very easy to follow a tactile representation of a density, but conversion to text is proving challenging. I suspect this is one situation where sonification of the curve might also prove to be an answer.



Cheers,

Jonathan







-----Original Message-----

From: BlindRUG [mailto:blindrug-bounces at nfbnet.org] On Behalf Of Gjalt-Jorn Peters via BlindRUG

Sent: Thursday, 30 July 2015 6:29 p.m.

To: BlindRUG at nfbnet.org<mailto:BlindRUG at nfbnet.org>

Cc: Gjalt-Jorn Peters

Subject: [BlindRUG] Measures of modality: understanding distribution shapes



Dear BlindRUG readers,



I'm working on revising our first statistics course (in a psychology curriculum). We're updating it such that R can be used, to make it accessible to blind students.



I'm currently trying to figure out how to let blind students assess distribution 'shapes'. They can compute skewness and kurtosis, but it's also necessary to assess modality (how many 'mountains' there are). Is any of you familiar with any measures for this?



How do you normally assess the 'shape' of a distribution?



Thank you very much in advance, kind regards,



Gjalt-Jorn Peters

Dutch Open University



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