Table 7.5 PERCENTAGE OF SAMPLE VENDORS WITH QUALITY CONTROL (%) Formal Informal No of Vendors with ISO certification 59.1 48.3 If yes, which one ISO 30.0 50.0 ISO 10.0 0.0 ISO/PS-16949:2002 20.0 0.0 ISO -14001:2004 0.0 0.0 ISO 30.0 50.0 ISO /TSI 6949/2009 10.0 0.0 Source Estimated from Survey Data. A multiplicity of factors were identified which impeded success in quality control. Table 7.6 shows that for the formal vendors the three major factors were type of machines available (72.7 percent, worker skills (68.2 percent) and financial constraints (63.6 percent. For the informal segment these were worker skills (83.3 percent) and type of machinery available (58.3 percent.