Parametric test o A tradionnal way is to consider some hypotheses:Fa~N(ua,2) and F~N(ub,2),and the null hypothesis becomes ua =ub. Under Ho,the statistic =Xa-can be modelled as a normal distribution with mean 0 and variance2(). o The ASL is then computed: -(*-2 ∫+心e2 ASL= d0* √2π0a R.Dahyot (TCD) 453 Modern statistical methods 20059/22Parametric test A tradionnal way is to consider some hypotheses: Fa ∼ N (µa, σ2 ) and Fb ∼ N (µb, σ2 ), and the null hypothesis becomes µa = µb. Under H0, the statistic θˆ = xa − xb can be modelled as a normal distribution with mean 0 and variance σ 2 θˆ = σ 2 ( 1 m + 1 n ). The ASL is then computed: ASL = Z +∞ θˆ e −(θˆ∗−θˆ) 2 2σ2 θˆ √ 2πσθˆ dθˆ∗ R. Dahyot (TCD) 453 Modern statistical methods 2005 9 / 22