Figure 5.

An example of raw plaque count data taken from Sloutskin et al. (35). A viral solution was assayed in a plate of M = 3 × 10⁵ cells at dilution numbers d = 2, 3, 4, 5, 6, and 7 at a dilution factor of D = 10. The particle to PFU ratio is assumed to be Q = 1. For T = 3 separate trials, the number of plaques were counted at each dilution level. The bottom row of plates used as a control is ignored. For dilution numbers d = 2 and 3, the entire plate of cells shows cytotoxicity so that the numbers of plaques were undiscernible and, thus, the countable data starts at d_c = 4. For the old method featured in Eq. 13, the estimate for N₀ is ${\hat{N}}_0=1.19\times {10}^6$, and for the MLE derived from Eq. 15, ${\hat{N}}_0=1.26\times {10}^6$. This results in a relative difference of 5.5%. Furthermore, when applying these parameters and the ${\hat{N}}_0$ estimate to Eq. 17, we observe a 10.7% decrease in the estimate variation using the MLE technique. To see this figure in color, go online.