STATISTICAL ACCURACY TO BE EXPECTED FROM CELL COLONY ASSAYS; WITH SPECIAL REFERENCE TO THE SPLEEN COLONY ASSAY

Assays of cell populations which involve the counting of colonies have a degree of uncertainty due to the random nature of the cloning process. With some assays there are circumstances where the number of colonies available for counting seriously limit the accuracy of the measurements . In considering this question in relation to the spleen colony assay for haemopoietic stem cells a simple formula for the variability, dependent on the number of colonies counted, has been derived which is also applicable to other cloning assays. Comparison with two sets of thymidine suicide data in normal mice show that the formula agrees well with the experimental findings and demonstrates its usefulness in planning experiments.