Previous studies performed on TFT have received criticism in the medical literature. For example, an exploratory study done by Charles Figley, a psychologist who endeavored to find more effective treatments for post-traumatic stress disorder (PTSD). He examined four novel therapies with a six-month follow-up evaluation (using measures that were not used immediately post treatment) and did not conduct statistical significance testing to compare the therapies. The authors stated that "In contrast to conventional psychotherapy research, the SCD methodology is not meant to compare the various treatments, and thus does not necessarily meet the criteria proposed for empirically validated treatments, although it does meet some of those criteria," and also stated that "Unfortunately, because of problems with client screening and data collection, the study fell short of reaching its goals. Moreover, the nature of the study precludes comparison of the approaches, and such a comparison was never planned." The authors also noted that because they did not prescreen participants for PTSD, not all participants necessarily met the criteria for PTSD. The authors acknowledged that the study of TFT and the other three methods were incomplete, and noted that "these treatment approaches appear to be promising in helping clients remove the most painful aspects of their traumatic memories." The authors noted that all four approaches warranted further study.