Null element = 0

 

Example 1: Element number 0 means "Short", and "1" means "Tall". "9" means "this facet is not applicable".

Null = 9

Labels=

4, Height

0 = short

1 = tall

*

Data=

23,9,14,0,2 ; facet 2 does not participate, facet 4 has element number 0

23,7,14,1,4 ; all facets active

23,9,14,9,3 ; facets 2 and 4 not participating

 

Example 2: Null elements when element labels are identifiers in the data.

Facets =3 ; students, items, raters

Delements = N, 3L  ; element identifiers are numbers except for facet 3 when the identifiers are the rater names

Null = 0  ; the "does not apply" element is element number 0

Labels =

1, Students

100-150   ; 50 students, numbered 100 to 150

*

2, Items

1-10 ; these are MCQ items

21-25 ; these are essay-writing items

*

3, Raters

0 = None  ; no rater = the Null element

1 = George

2 = Martha

3 = Betty

*

Data =

52, 3, None, 1 ; student 52 succeeded on MCQ item 3 which has no rater

67, 24, Martha, 3 ; student 67 on essay item 24 was rated by Martha with a 3.

.....