As the aim of the study was to establish the feasibility of using early counting to predict the titration results that would be obtained in the standard method, our first approach was based on correlation analysis (Table 2) between the bacteriophage counts obtained at different times against the counts obtained at 18 hours according to the ISO procedure.
Pearson correlations for sewage and river samples
| Pearson correlation (countih v count18 h) . | |||||
|---|---|---|---|---|---|
| Hour . | Sewage (1:100) . | Sewage (1:1,000) . | Sewage (1:10,000) . | River (undiluted) . | River (1:10) . |
| r . | r . | r . | r . | r . | |
| 2 | 0.690 | 0.475 | 0.637 | 0.918 | 0.736 |
| 3 | 0.928 | 0.856 | 0.728 | 0.961 | 0.857 |
| 4 | 0.968 | 0.915 | 0.842 | 0.983 | 0.887 |
| 5 | 0.980 | 0.947 | 0.839 | 0.988 | 0.891 |
| 6 | 0.988 | 0.977 | 0.849 | 0.991 | 0.925 |
| 18 | 1.000 | 1.000 | 1.000 | 1.000 | 1.000 |
| Pearson correlation (countih v count18 h) . | |||||
|---|---|---|---|---|---|
| Hour . | Sewage (1:100) . | Sewage (1:1,000) . | Sewage (1:10,000) . | River (undiluted) . | River (1:10) . |
| r . | r . | r . | r . | r . | |
| 2 | 0.690 | 0.475 | 0.637 | 0.918 | 0.736 |
| 3 | 0.928 | 0.856 | 0.728 | 0.961 | 0.857 |
| 4 | 0.968 | 0.915 | 0.842 | 0.983 | 0.887 |
| 5 | 0.980 | 0.947 | 0.839 | 0.988 | 0.891 |
| 6 | 0.988 | 0.977 | 0.849 | 0.991 | 0.925 |
| 18 | 1.000 | 1.000 | 1.000 | 1.000 | 1.000 |