In order to make and successfully obtain a valid testthere are some conditions which must necessarily happen. These conditions are:fairness of the test, reliability of the test and accuracy. Fairness of thetest is obtained when only the desired independent variable changes whilst thecontrol variables are kept constant. In my experiment I needed to be carefuland precise in cutting the potato to my previously chosen lengths. All my othervariables had been kept the same such as substrate concentration, temperature,same tuber and so on, in order to consider my experiment a fair test.

                   Inorder for a test to be considered reliable, results have to be similar and itwould be ideal to repeat the investigation more than once in order to create amean between the results. I repeated the test for three times, reproducing eachtime the same experiment with the same equipment and same variables.