486 
u — (r — 1) v^n + 1 
If Xj are independently distributed u is approximately normally 
distributed with zero mean and unit varianee if n > 20. If we test a 
hypothesis of independence between x with a test size a the critical 
region is u ^ u a . This test was applied to selected primary data in the 
investigations of setting precision. The test indicated that the depen 
dence between two successive settings was highly significant. The con 
dition of independence of the random variables, which commonly is 
assumed to hold when applying the method of least squares and most 
other statistical methods, is therefore not met. 
The investigations reported above should be considered in the light 
of this fact. 
A cknowledgenients 
These investigations have been performed at the Royal Institute of 
Technology, Division of Photogrammetry, Stockholm, Sweden. The 
investigations were planned by B. Hallert, Dr Techn. The alcohol in 
vestigation was made in collaboration with Ivarolinska Instituted De 
partment of Alcohol Research, Stockholm, Sweden. L. Goldberg, Dr 
Med. planned the alcohol investigation together with B. Hallert. The 
following persons participated: B. Adolfsson, O. Ellsten, G. Fager- 
holm, I. Hadem, J.-E. Haggroth, C. O. Jonasson, P. Kaasila, B. Lind 
quist, H. Middel, A. Moren, E. Rehnlund, Raman, N. Social, J. Talts, 
E. Tenhunen, E. Wernholm, S. Wilson and the author. P. Borchers 
has brushed up the translation. 
Reference 
1. Hold, A.: Statistical Theory with Engineering Applications. — John Wiley 
and Sons Inc., New York, 1952.