these division in today's world doesn't even count as these divisions never aimed to divide nations in various category in the first place.a nation,in the size of singapore can easily qualify for first world,cause their per capita income is high.but lets think the counter argument,shall we????
It should also be pointed out that city-states such as Singapore and Monaco do not belong in this study since they are nations in name only. Without exception, they do not have extensive borders to defend, or rural areas to develop, and they must depend on other nations to protect them. Large cities are by and large the centers of wealth generation, that’s where the factories and the best schools and universities, and where the largest businesses are based. Those who disagree with this need only look at the list of states that pay more federal taxes than they receive as compared to the list of states that receive more federal taxes than they pay. Almost without exception, it is the urban states that pay more and the rural states that receive more. Therefore it is apparent, if not proven to the level of scientific fact, that in any study of what the most successful governmental system may be, city-states must be considered an exception to the rule that does not disprove the rule.
so,its not the "First World Status" thats push your country forward.any country can have disparity of Education level,income etc between its civilians of Rural and Urban states,and that'll drag your rank.the only tag that is truely helpful is "developed" and "developing"...
by the way,its GDP(PPP) that is the measurement of this ranking...