The buttons were randomly chosen from six boxes, that each contained about 80 buttons each, that my sister used for an art project a few months ago.  She randomly selected these buttons herself, and she didn’t choose for them to be any particular material, color, or size.  She had them stored in 6 different small boxes, for no particular reason.  I didn’t see any significant differences between the content of the boxes, she may have just needed a certain amount at a time when she was working on the project.  I chose about 5 buttons from each box (six from the sixth box).  Below explains the variables and how they were measured:

BOX:
There were 6 different boxes.

PARTS:
This variable denotes the number of sections in her project that that particular button was used for.

COLOR:
0 – white
1 – black
2 – blue/green
3 – yellow/orange
4 – pink
5 – brown/beige

PLASTIC:
1 – yes
0 – otherwise