glass: Glass composition data for seven elements from 200 glass...

Description Usage Format Details Source References

Description

These data are from Grzegorz (Greg) Zadora at the Institute of Forensic Research in Krakow, 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.

Usage

1

Format

a data.frame with 2400 rows and 9 columns.

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

Details

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".

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

Source

Grzegorz Zadora Institute of Forensic Research, Krakow, Poland.

References

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


comparison documentation built on Aug. 5, 2020, 5:07 p.m.