This study is aims at determining the inter laboratory variation when using the thrombin generation assay calibrated automated thrombogram (TGA CAT). It is thus, not a clinical trial in its usual meaning. However, to achieve relevant test samples one patient will be treated with two different study drugs as part of the trial and therefore, approval by Läkemedelsverket is needed. Test plasma samples will be sent out to five participating centers in the Scandinavian countries (Gothenburg and Stockholm, Sweden, Århus Denmark, Oslo Norway and Helsinki Finland) and coefficients of variance (CV) and level of agreement will be analyzed. To obtain representative plasma samples with a wide range of thrombin generation capacity (TGC), blood samples will be collected from research persons that has given informed consent to participate in the study. To obtain plasma with low TGC, blood samples will be drawn from patients with severe hemophilia (n=4)(study group 1), to obtain plasma with normal TGC, blood samples will be drawn from healthy volunteers (n=3)(study group 2) and to obtain plasma with high TGC, plasma will be collected from healthy volunteers (n=3)(study group 3) that at previous measurements have been shown to have a TGC>2SD of the median of the control population. Moreover, one patient with severe hemophilia A (HA) will be treated with two factor FVIII concentrates, one with standard half- life (Advate™) and one with a pro-longed half-life (Adynovate™) at two separate occasions (Treated HA person). By taking repeated blood samples after administration, samples with a wide range of FVIII levels and TGC:s will be obtained. Moreover, the effect of using plasmas with low, normal and high TGC for normalization will be investigated. Plasma samples will be collected as soon as approval from the Swedish medical agency (SMA) has been obtained, we count on sending them to participating centers March 2017. All laboratory measurements, data analysis and report writing will be concluded before December 31 2017.