factors that concern the economic contribution include for example the motives which encourage immigrants to work in these sectors the knowledge and skills they bring the innovation generated directly or indirectly by them and possible negative economic or related effects eg pressure on nativebom employment infrastructure price levels or the environment however these national results do not necessarily hold for each economic sector since even within the same sector employment creation and displacement effects may occur simultaneously the study discussed in this chapter illustrates such effects and in this way complements the analysis in other chapters wholesale and retail trade is a very important sector in terms of employment and almost one in five workers are employed in this sector the share of employment in mining is far lower just above but at the same time this sector accounts for almost of gdp compared with for trade ghana statistical service