Free parameter

{{Short description|Variable in a mathematical model}}

{{confused|Free variable}}

A free parameter is a variable in a mathematical model which cannot be predicted precisely or constrained by the model{{Cite book|title = Principles and Practice of Structural Equation Modeling|url = https://books.google.com/books?id=Q61ECgAAQBAJ|publisher = Guilford Publications|year= 2015|isbn = 978-1462523351|language = en|first = Rex B.|last = Kline|page = 128}} and must be estimated{{Cite book|title = The Handbook of Multisensory Processes|url = https://books.google.com/books?id=CZS_yDoFV7AC|publisher = MIT Press|year= 2004|isbn = 978-0262033213|language = en|first = Gemma|last = Calvert|first2 = Charles|last2 = Spence|first3 = Barry E.|last3 = Stein|page = 160}} experimentally or theoretically. A mathematical model, theory, or conjecture is more likely to be right and less likely to be the product of wishful thinking if it relies on few free parameters and is consistent with large amounts of data.