Robert Carter Jun 11, 2016:

@Taña On further reflection, I think, given the entry in Merriam-Webster pointed to by Phil's reference, we'll have to concede that polychotomous, while erroneous at its origin, does in fact exist, and has done for quite some time.
There does, however, appear to be some difference between the two words, if we are to believe the Oxford:

polychotomy
NOUN
Division into more than two parts or groups; especially ( Taxonomy ) the division of a taxonomic grouping into more than two subgroups; an instance of this.
http://www.oxforddictionaries.com/definition/english/polytom...

cf

polytomy
NOUN
1 Logic and Statistics . A division or classification into several (usually more than three) groups or subsets; (in later use also) the assignment of three or more possible values to a categorical variable.
2 Biology and Taxonomy . Division into more than two branches at the same point or node; the occurrence of such branching.
http://www.oxforddictionaries.com/definition/english/polytom...

So, perhaps "polytomous" is the word that should be used, in any case, and "polychotomous", a solecism originally coined in taxonomy, has mistakenly gained currency in statistics literature.

Taña Dalglish Jun 11, 2016:

@ Francois Two against one. The word "polychotomous" should NOT exist, despite your insistence that the link Phil provided cannot be disputed (American Statistical Association). In fact, the one I found (Penn State) makes explicit mention that the word "polychotomous" is non-existent. Furthermore, perhaps if you care to read Robert's entry regarding the etymology of the word, you may change your mind. Following Robert's line of reasoning, and I am agreeing with him, the use of "polychotomous" is erroneous, and if we are to follow the etymology. Regards.

Robert Carter Jun 11, 2016:

Polytomous and dichotomous Yes, Taña, you're right, polychotomous doesn't exist. It's probably from a misunderstanding of the roots of the word. They've lopped the "di-" off "dichotomous" and put "poly-" in front of "chotomous", whereas the prefix is actually "dicho-", not "di-". It's like saying monogamous and polynogamous (instead of polygamous).

The term dichotomy is from the Greek language διχοτομία dichotomía "dividing in two" from δίχα dícha "in two, asunder" and τομή tomḗ "a cutting, incision".
https://en.wikipedia.org/wiki/Dichotomy

Taña Dalglish Jun 10, 2016:

I am only playing devil's advocate here, but according to this link, the word "polychotomous" does not exist, but I must be careful to say that it appears quite frequently in literature, which then raises the question, "Who is right?", or "two schools of thought"?

8.1 - Polytomous (Multinomial) Logistic Regression | STAT 504
https://onlinecourses.science.psu.edu/stat504/node/172
We have already learned about binary logistic regression, where the ... (Note: The word polychotomous is sometimes used, but this word does not exist!).

Logistic Regression Models for Multinomial and Ordinal Variables
www.theanalysisfactor.com/logistic-regression-models-for-mu...
The multinomial (a.k.a. polytomous) logistic regression model is a simple extension of the binomial logistic regression model. ... In multinomial logistic regression the dependent variable is dummy coded into multiple 1/0 variables. ... The mulitnomial logistic regression then estimates a ...

It could not be further from my working field, so I leave it at that. Regards.

matt robinson Jun 10, 2016:

binomial or polynomial logistic regressions...I think. I haven't come across 'policotomica' I have also seen binary instead of binomial. Perhaps this is a good starting point, anyway.