sample and population造句

This difference can be rewritten as the sum of two terms : the difference in expected risk between the sample and population iterations and that between the population iteration and the regression function:
The "'root-mean-square deviation ( RMSD ) "'or "'root-mean-square error ( RMSE ) "'is a frequently used measure of the differences between values ( sample and population values ) predicted by a model or an estimator and the values actually observed.
It's difficult to find sample and population in a sentence. 用sample and population造句挺难的