What is the significance of this error? What does this tell me about these two samples?. I added the coeficients for the donor then re-calculated the fit. > donor.fit = lmFit(MA, design.III) Coefficients not estimable: HISS0039 HISS0050 The design matrix I used was as follows, you can see that there is a column of 1's that represent that the first 16 samples are for donor HISS0033, the rest of the matrix for each donor looks the same but with the 1's in the rescpective donor column: X A_0h A_24h A_6h A_72h B_0h B_24h B_6h B_72h C_0h C_24h C_6h C_72h N_0h N_24h N_6h N_72h HISS0033 HISS0036 HISS0037 HISS0038 HISS0039 HISS0050 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 2 2 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 3 3 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 4 4 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 5 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 6 6 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 7 7 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 8 8 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 9 9 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 10 10 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 11 11 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 12 12 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 13 13 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 14 14 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 15 15 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 16 16 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0