In　a　recent　paper　by　Wang　and　Yang　(2007)　[6],　a　pair　of　bounded　data　envelopment　analysis　(DEA)　models　were　proposed　to　measure　the　overall　performances　of　a　group　of　decision-making　units　(DMUs),　which　were　characterized　by　interval　efficiencies.　In　this　paper,　we　show　by　a　numerical　example　that　the　bounded　DEA　models　are　incapable　of　determining　an　efficiency　interval　for　any　DMU　when　there　is　a　zero　value　for　each　output.　A　pair　of　improved　bounded　DEA　models　is　thus　proposed　to　overcome　the　drawback.　Another　example　involving　performance　measurement　of　countries　participating　in　the　Athens　2004　Summer　Olympic　Games　is　presented　to　show　that　the　proposed　approach　is　an　effective　and　practical　method　for　performance　analysis　in　real　world　situations.　(c)　2012　Elsevier　Ltd.　All　rights　reserved.