According to ACI 214-77 (References 2) the Within-Test Standard of Concrete Control is related to the average Test Coefficient of Variation of a set of Test Strengths and to the Class of Operation as in the following tables.
| Field Control Testing | Laboratory Trial Batches | ||
| Average Test Coefficient of Variation (%) | Standard of Control | Average Test Coefficient of Variation (%) | Standard of Control |
| below 3.0 | Excellent | below 2.0 | Excellent |
| 3.0 to 4.0 | Very Good | 2.0 to 3.0 | Very Good |
| 4.0 to 5.0 | Good | 3.0 to 4.0 | Good |
| 5.0 to 6.0 | Fair | 3.0 to 4.0 | Fair |
| above 6.0 | Poor | above 5.0 | Poor |
These values are obtained from table 3.5 Standards of Concrete Construction of ACI 214-77.