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Dear FSL users, I’m currently working on a TBSS analysis using a sample size of approximately 150 children. I have a number of clinical variables that may be used as an explanatory variable. Normally, when I would perform a linear regression analysis, I would start with univariate testing to identify any possible explanatory variables. Any significant variables would then be included in multivariate analyses. Does it make sense to apply the same for TBSS? As age is a wel known variable to affect FA in (young) children), so I would like to combine each variable with age at scan. So for example, a first ‘univariate analysis’ could be gender combined with age at scan, next presence of disease (yes/no) and age at scan, etc. All variables that are significant would then be included in a multivariate TBSS model. If the above does make sense, what should I then do with variables that show a significant association with FA in the ‘univariate’ analysis but show no correlation in multivariate analyses. For example, if gender affects FA when analyzed with age only (as mentioned above), but shows no effect on FA when combined with presence of disease (yes/no), number of medicine and age at scan. Would it then make sense to remove the gender variable? And finally, is there a maximum of variables that can be used in a TBSS model? Thanks for your help, Niek ------------------------------------------------------------------------------ De informatie opgenomen in dit bericht kan vertrouwelijk zijn en is uitsluitend bestemd voor de geadresseerde. Indien u dit bericht onterecht ontvangt, wordt u verzocht de inhoud niet te gebruiken en de afzender direct te informeren door het bericht te retourneren. Het Universitair Medisch Centrum Utrecht is een publiekrechtelijke rechtspersoon in de zin van de W.H.W. (Wet Hoger Onderwijs en Wetenschappelijk Onderzoek) en staat geregistreerd bij de Kamer van Koophandel voor Midden-Nederland onder nr. 30244197. Denk s.v.p aan het milieu voor u deze e-mail afdrukt. ------------------------------------------------------------------------------ This message may contain confidential information and is intended exclusively for the addressee. If you receive this message unintentionally, please do not use the contents but notify the sender immediately by return e-mail. University Medical Center Utrecht is a legal person by public law and is registered at the Chamber of Commerce for Midden-Nederland under no. 30244197. Please consider the environment before printing this e-mail.