private void doubleToBD(){
    
        this.responsesBD = new BigDecimal[this.nGroups][];
        for(int i=0; i<this.nGroups; i++){
            this.responsesBD[i] = new BigDecimal[this.nResponsesPerGroup[i]];
            for(int j=0; j<this.nResponsesPerGroup[i]; j++){
                this.responsesBD[i][j] =  new BigDecimal(responses0[i][j]);
           }
        }
    }