186 



SAMPLING NORMAL POPULATIONS 



Ch. 6 



(c) As n was increased, the distribution of x, and its mean and vari- 

 ance, approached more and more closely to those features which the 

 Central Limit Theorem assures us will be attained if n is sufficiently 

 large. 



The foregoing discussions are not intended to make us ignore the 

 non-normality of distributions met in practice, but they do indicate 

 that a great many moderately non-normal distributions can be studied 

 by means of the techniques explained in this chapter. 



In this chapter the ratio (x — m)Ax was said to follow the ^-dis- 

 tribution with the same number of degrees of freedom that s^ has as 

 a sampling estimate of a^. Actually any ratio {w — /x)/s will follow 



TABLE 6.714 



summary of counts of flies on dairy cattle tethered in a fleld at 

 Kansas State College After They Were Sprayed with an Effective 



Fly Repellent 



