| Value | Category | 
                                    
                    
                        | 0 | Never used a computer | 
                                    
                    
                        | 1 | My teacher | 
                                    
                    
                        | 2 | My friend | 
                                    
                    
                        | 3 | My family | 
                                    
                    
                        | 4 | Myself | 
                                    
                    
                        | 5 | Others | 
                                    
                    
                        | Sysmiss |  | 
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.