500 items requested
40 items
not acquired
45 items in
circulation
67 items not in correct
location on shelves
17 items not located
on shelves by user
PS = PA × PC × PL × PU 
PS = .66
PA = .92
PL = .84
PU = .95
PC = .90
User barrier
Acquisition barrier
Circulation barrier
Library barrier
Number of items
415 items not in
circulation
348 items in correct
location on shelves
331 items correctly
located on shelves
by user
460 items acquired
Adapted from Kantor (76)