## 2 Materials and Methods
### Selection of Input Parameters  
The first phase focused on the selection of 30 kinematic parameters, which provided the basis for choosing the 16 parameters of the UBI indicator. Taking into consideration the mathematical algorithm, it was assumed that the parameters had to be presented in the form of a single numerical value. Thirty parameters were selected following consultations with physiotherapists and physicians at the Miners' Rehabilitation Centre GCR \"REPTY\", as well as on the basis of the authors' experience. The shortlisted parameters were selected from kinematic data collected during the analysed activity of drinking from a mug. The following kinematic and temporal parameters were selected for the analysed activity:  
* P1--Duration of the lifting phase t1 [s]--time from the moment of gripping the mug to the beginning of the drinking phase, which was defined as the lips touching the mug;
* P2--Duration of the lowering phase t2 [s]--time from the moment of the beginning of the movement after the drinking phase to the moment of placing the mug back onto its starting position;  
ximum spine anteversion angle;P19--Minimum spine rotation angle;
* P20--Maximum spine rotation angle;
* P21--Minimum spine anteversion angle in section Th1-Th12;
* P22--Maximum spine anteversion angle in section Th1-Th12;
* P23--Minimum spine rotation angle in section Th1-Th12;
* P24--Maximum spine rotation angle in section Th1-Th12;
* P25--Minimum spine anteversion angle in section L1-L5;
* P26--Maximum spine anteversion angle in section L1-L5;
* P27--Minimum spine rotation angle in section L1-L5;
* P28--Maximum spine rotation angle in section L1-L5;
* P29--Abduction/adduction motion range of the shoulder joint;
* P30--External/internal rotation motion range of the shoulder joint. The next phase involved surveying of physicians and physiotherapists in order to understand their experience of examining motor functions in the upper limbs of patients after stroke. In the survey, these healthcare professionals indicated their specialisation and provided answers related to their experience in the treatment/rehabilitation of patients after ischaemic stroke, gave an estimation of the number of treated/rehabilitated patients after ischaemic stroke, and the level of their knowledge in the application of biomechanical systems to the rehabilitation of patients after ischaemic stroke. In order to aid in the selection of parameters for the development of the new indicator, they were asked: \"In your opinion, which parameters have the highest diagnostic value in the assessment of motor functions of the upper limbs in patients after cerebral stroke?\" They were then asked to select the 16 most significant parameters from a set of 30 identified by the authors. The survey was sent by e-mail to 50 physicians and physiotherapists and a total of 25 replies were received. Next, the 16 parameters necessary for the development of the UBI indicator were selected using the following criteria:  
* The percentage distribution of parameters beyond the standard (M1);
* The differences in mean values between the reference group and the patient group (M2);
* The variability of parameters (M3). 4.1 Selection of Parameters Taking into Account the Percentage Distribution of Parameters beyond the Standard (M1)  
Selection of input parameters was based on the qualification of results obtained for the stroke patients with upper limbs paresis, with up to 4 ranges defined by the mean value and standard deviation obtained from the reference group (Table 1). The ranges are marked by green, yellow, orange or red, which indicate the difference between the result of a certain parameter obtained for a given patient and the result obtained for the reference group. Boundary values of the ranges were defined using the mean value and standard deviation obtained in the reference group, for both the dominant and non-dominant upper limb, respectively.