GlassRI 01: Grouping refractive index data by SKM2 using Excel
 

Assume that eight fragments have been recovered from a suspect.  These fragments have refractive index, RI, values (each the average of several GRIM measurements) given by:

 

1.52397

1.52433

1.52427

1.52381

1.52397

1.52396

1.52426

1.52400

 

The control samples submitted have RI values with a standard deviation = 4.1610-05


Use the SKM2 algorithm to check for sub-groups within the data by calculating appropriate values of
l*.

Use the standard deviation of the control as an estimate for the standard deviation of the recovered group.


Video Answer: l* = 177, 17.3, 3 groups