In the general equation the expression F₁  quantifies the distinctive contribution to yarn tenacity of yarn irregularity that is inevitable in roller drafting. The expressions F₂,F₃ and F₄ quantify the distinctive contribution of twist that has necessarily to be introduced into the drafted fleece to convert it into formed yarn.The algebraic expressions for F₂ and F₃  derived from data from the first set of ATIRA ring-spun yarns are remarkably similar to those derived from Brown’s data on ring-spun yarns. Also the expressions from the first ATIRA spinning are found to be valid for three other ring-spun yarns, each on a different drafting system. Furthermore for all these five spinnings Bogdan’s expression for F₄  is applicable.

We can take advantage of these findings in making use of the equation in practice. For any one system of cotton and yarn testing, we need derive the regression constants in the expressions for F₂ and F₃ only once; we can then use them for any ring-spun yarn; only the numerical constants in the expression for F1 need to be determined anew for any different drafting system. The determination of these constants requires only the spinning of each of five different cottons to three different counts, each cotton at any one convenient twist.

The availability of these constants is of great help in cotton assessment. Immediately after carrying out the fibre tests on any cotton, the laboratory can trace out the CS – M curves for a range of counts of yarn of likely interest to the spinner. All that is required is the storage in a computer of the requisite programme for the numerical evaluation of the expressions for F1, F2, F3 and F4. and for curve-tracing. 

The sequence of steps to estimate the CS is listed in Appendix II - 2.