Figure 4
From: A method to estimate the efficiency of gene expression from an integrated retroviral vector
An example of the calculation to estimate the proportion of cells resistant to puromycin. Data from table 2 was plotted into a graph. In the graph, the vertical axis (y) is logC, the horizontal axis (x) is logP0 (see table 2). From the linear equation derived from the graph, 
. Therefore, after 21 days of selection in puromycin, the proportion of puromycin resistant cells in the original sample P0 and the cell count C is related by the equation 
. This relationship allowed the proportion of puromycin resistant cells in the sample to be determined. A more accurate estimate was obtained by averaging the P0 of the sample obtained by similar calculations performed for cell counts obtained on different days of culture in puromycin.