In this two part episode we discuss the fine art of preregistration. We go back into the history of preregistration, its evolution, and current use. Do we preregister to control the Type 1 error rate, or to show that we derived our prediction from theory a priori? Can and should we preregister exploratory or secondary data analysis? And how severe is the issue of severe testing?   Shownotes ClinicalTrials.gov You can preregister on AsPredicted and the OSF Johnson, M. (1975). Models of Control and Control of Bias. European Journal of Parapsychology, 36–44. SPIRIT Checklist Bishop, D. V. M. (2018). Fallibility in Science: Responding to Errors in the Work of Oneself and Others. Advances in Methods and Practices in Psychological Science, 1(3), 432–438. https://doi.org/10.1177/2515245918776632 FDA trials tracker: https://fdaaa.trialstracker.net  Ensinck, E., & Lakens, D. (2023). An Inception Cohort Study Quantifying How Many Registered Studies are Published. PsyArXiv. https://doi.org/10.31234/osf.io/5hkjz van den Akker, O. R., van Assen, M. A. L. M., Enting, M., de Jonge, M., Ong, H. H., Rüffer, F., Schoenmakers, M., Stoevenbelt, A. H., Wicherts, J. M., & Bakker, M. (2023). Selective Hypothesis Reporting in Psychology: Comparing Preregistrations and Corresponding Publications. Advances in Methods and Practices in Psychological Science, 6(3), 25152459231187988. https://doi.org/10.1177/25152459231187988 Claesen, A., Gomes, S., Tuerlinckx, F., & Vanpaemel, W. (2021). Comparing dream to reality: An assessment of adherence of the first generation of preregistered studies. Royal Society Open Science, 8(10), 211037. https://doi.org/10.1098/rsos.211037 Bakan, D. (1966). The test of significance in psychological research. Psychological Bulletin, 66(6), 423–437. https://doi.org/10.1037/h0020412 Rosenthal, R. (1966). Experimenter effects in behavioral research. Appleton-Century-Crofts. Johnson, M. (1975). Models of Control and Control of Bias. European Journal of Parapsychology, 36–44. de Groot, A. D. (1969). Methodology. Mouton & Co. Claesen, A., Lakens, D., Vanpaemel, W., & Dongen, N. van. (2022). Severity and Crises in Science: Are We Getting It Right When We’re Right and Wrong When We’re Wrong? PsyArXiv. https://doi.org/10.31234/osf.io/ekhc8