BS 6954-2:1988

National foreword
Committees responsible
Recommendations
1 Scope
2 Field of application
3 Reference
4 General
5 Probability and induced deviations
6 Combination of random variables
Annex
   Sampling and the calculation of the standard
   deviation
Figures
1 Gaussian curves (normal distribution for different
   standard deviations)
2 Limits corresponding to 1, 2 and 3 times the standard
   deviation
3 Distribution of values (a) and distribution of
   deviations (b), with illustration of limits (c)

Shows how inaccuracies can be treated as both random and systematic, with the random variability following a normal distribution.

This International Standard describes the fundamental characteristics of dimensional variability in building and of the particular case of combination of random unrelated variables; it sets out the need to relate dimensional variability to the limits imposed on joint widths by the need for satisfactory functioning.