glass: Data - elemental composition of glass

Description Usage Format Details Source References Examples


Greg Zadora's glass composition data for seven elements from 200 glass items.




item factor - 200 levels - which item the measurements came from
fragment factor - 4 levels - which of the four fragments from each item the observations were made upon
logNaO numeric - log of sodium concentration to oxygen concentration
logMgO numeric - log of magnesium concentration to oxygen concentration
logAlO numeric - log of aluminium concentration to oxygen concentration
logSiO numeric - log of silicon concentration to oxygen concentration
logKO numeric - log of potassium concentration to oxygen concentration
logCaO numeric - log of calcium concentration to oxygen concentration
logFeO numeric - log of iron concentration to oxygen concentration


These data are from Greg Zadora at the Institute of Forensic Research in Cracow, Poland. They are the log of the ratios of each element to oxygen, so logNaO is the log(10) of the Sodium to Oxygen ratio, and logAlO is the log of the Aluminium to Oxygen ratio. The instrumental method was SEM-EDX.

The item indicates the object the glass came from. The levels for each item are unique to that item. The fragment can be considered a sub-item. When collecting these observations Greg took a glass object, say a jam jar, he would then break it, and extract four fragments. Each fragment would be measured three times upon different parts of that fragment. The fragment labels are repeated, so, for example, fragment "f1" from item "s2" has nothing whatsoever to do with fragment "f1" from item "s101".

These data are a list. If some object more matrix like is needed convert using

For two level models use "item" as the lower level - three level models can use the additional information from the individual fragments.


Grzegorz Zadora Institute of Forensic Research Cracow, Poland.


Aitken, C.G.G. Zadora, G. & Lucy, D. (2007) A Two-Level Model for Evidence Evaluation. Journal of Forensic Sciences: 52(2); 412-419.



Example output

comparison documentation built on May 29, 2017, 9:08 a.m.