| Value | Category | 
                                    
                    
                        | 1 | pay agency shop fee | 
                                    
                    
                        | 2 | be organised in a union | 
                                    
                    
                        | 3 | neither: be unorganised | 
                                    
                    
                        | 4 | no preference | 
                                    
                    
                        | 9 | no answer | 
                            
            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.