# 40. Discard unfavourable data ## 40.5. Methodology/Refinements/Sub-species ### 40.5.3. Switching dependent variables Another common technique of selective manipulation is to perform a study that tests a large number of dependent (response) variables at the same time and then only choose those that show some kind of significant correlation, dumping the rest. For instance, a study testing the effect of a medical treatment might use as dependent variables the probability of survival, the average number of days spent in the hospital, the patient's self-reported level of pain, etc. This also increases the likelihood that at least one of the variables will, by chance, show a correlation with the independent (explanatory) variables. This is a statistically fraudulent approach, but if it is managed honestly, it could be useful in generating alternative research lines.