APPENDIX E— STATISTICAL RELIABILITY ANALYSIS 



Statistical Reliability oF Major Findings Standard Error of Estimated Number of Persons 



of the I960 Survey 



(Range 68 chances out of 100] 



The standard error is primarily a measure of sampling variability; that is, the 

 variations that might occur by chance because only a sample of the population is 

 suri^eyed. The chances are about 2 out of 3 that an estimate from the sample would 

 differ from a complete census by less than the standard error. The chances are 

 about 19 out of 20 that the difference would be less than twice the standard error, and 

 about 99 out of 100 that it would be less than 2Vi times as large. 



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