| Value | Category | 
                                    
                    
                        | 1 | Pre-escolar | 
                                    
                    
                        | 2 | Primaria | 
                                    
                    
                        | 3 | Secundaria | 
                                    
                    
                        | 4 | Universitaria | 
                                    
                    
                        | 7 | Missing | 
                                    
                    
                        | 9 | No sabe/NR | 
                                    
                    
                        | 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.