Africa, Portugal. Portuguese trading stations in West Africa and the slave trade. Portuguese expansion into Africa began with the desire of King John I to gain access to the gold-producing areas of West Africa.ortuguese trading stations in East Africa and the Slave trade. A map drawn in Spain dated 1375, showing the king of Mali holding a gold nugget. Source: British Library. Well-established gold and ivory trade network existed between African kingdoms in the interior and cities on the east coast of Africa.
Statistical analysis is used in quantitative research to collect, organize, and describe empirical data. All quantitative studies rely on statistical analyses because quantitative research is a method of approaching questions that is based on concrete, observable, objective, and measurable data.
Regression analysis can be a very powerful tool, which is why it is used in a wide variety of fields. The analysis captures everything from understanding the strength of plastic to the relationship between the salaries of employees and their gender.'ve even used it for fantasy football ! But there are assumptions your data must meet in order for the results to be valid. In this article, I'm going to focus on the assumptions that the error terms (or residuals) have a mean of zero and constant variance.