I am no mathematician, but I have used KS tests to compare kill-patterns
based on sheep and goat mandibles. In this case, there is a natural order of
the age classes from youngest to oldest.
Pam Crabtree
----- Original Message -----
From: "D.C. Orton" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, January 11, 2008 5:42 AM
Subject: Re: [ZOOARCH] Statistics help
> Whether the data are at the taxon or the element level, the arguments
> surrounding NISP and MNE/MAU are still entirely relevant. The only
> difference is that when dealing with elements you only have to worry about
> one, rather than two, levels of fragmentation of the unit of analysis (the
> element)- i.e. only breakage of elements, not disarticulation. You can
> restrict the 'NISP' and 'MN*' labels to taxonomic comparisons if you want,
> but there's still a fundamental difference between fragment counts and
> derived estimates when dealing with elements. Surely? Unless I'm missing
> something?
>
> Not that it matters enormously in the present case, because neither group
> of measures is really amenable to classical hypothesis testing in any
> case. I know that zooarchaeologists frequently use chi-squared etc. with
> both forms, but quite simply they shouldn't, especially with raw counts.
> This is equally the case whether those counts are of individuals or of
> elements, UNLESS there is virtually no breakage. Some form of Watson-style
> DZ is probably the best bet, but even then you have to worry about
> non-independence between proximal and distal ends etc.
>
> With regard to the use of Kolmogorv-Smirnov tests for element profiles,
> I'm not an expert on this stuff either and I have to admit I haven't read
> that book in detail, but it sounds like madness to me. Even if one ignores
> the quantification/sample inflation issue, K-S is designed for ordinal
> data, while element profiles are nominal. The KS test statistic is based
> on Dmax, the greatest difference between the cumulative frequency curves
> of the two distributions. With element profiles this will differ depending
> on the order in which you list the elements - an unscrupulous researcher
> could even try a few different orders to get the 'best' result.
>
> I may well be missing something here, in which case I'd be grateful if
> someone could explain where I'm off the mark. I'd love to be wrong on
> this.
>
> David
>
>> The OP can speak for herself, but I took her statement literally:
>> "differences in element frequencies between the two units."
>>
>> If elements have been counted, then issues of NISP versus MNI are not
>> relevant to her question.
>>
>>
>>>
>>>Subject: Re: [ZOOARCH] Statistics help
>>> From: "D.C. Orton" <[log in to unmask]>
>>> Date: Thu, 10 Jan 2008 22:25:17 +0000
>>> To: [log in to unmask]
>>>
>>>I think the most important question is what form of quantification you're
>>>using.
>>>
>>> If it's NISP-based, you can basically forget formal hypothesis testing
>>> as you're samples are almost certainly subject to sample inflation (see
>>> e.g. Grayson 1984, pp.22-23 for a clear explanation of this). The only
>>> exception would be if the bones are barely fragmented at all. Of course,
>>> if you run the tests (chi-squared would make sense by the sound of it)
>>> and find no significant pattern then that's fine, as sample inflation
>>> will only ever lower your p values, but you shouldn't trust an
>>> apparently significant result from this kind of data.
>>>
>>>To be honest, if it's minimum-number based the situation isn't great
>>>either, since you're then dealing with estimates with a non-random,
>>>asymmetrical error term.
>>>
>>>Frankly, zooarchaeological data is a bit of a nightmare statistically
>>>speaking. David
>>>
>>>> You don't say how many elements you have, but whether it is one or more
>>>> then I would have thought Chi-square and Fisher's test are entirely
>>>> appropriate. Why are you worried about using them?
>>>>
>>>>
>>>>>
>>>>>Subject: [ZOOARCH] Statistics help
>>>>> From: Melanie Fillios <[log in to unmask]>
>>>>> Date: Thu, 10 Jan 2008 15:39:26 -0600
>>>>> To: [log in to unmask]
>>>>>
>>>>> Dear All, I'm hoping someone may be able to point me in the right
>>>>> direction with some statistical analysis of an assemablage. In short,
>>>>> I am comparing two stratigraphic units and would like to test whether
>>>>> differences in element frequencies between the two units are
>>>>> statistically significant. Could anyone tell me what type of test I
>>>>> should be using? I've looked a using a Chi-square or Fisher's test,
>>>>> but neither seem appropriate. As math is not my strong point, I may be
>>>>> missing something.
>>>>>
>>>>>Thanks for the help!
>>>>>
>>>>>Melanie
>>>>>
>>>>>Dr. Melanie Fillios
>>>>>University of Sydney
>>>>>NSW, Australia 2006
>>>>>[log in to unmask]
>>>>
>>
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