Essay --

Longitudinal research was used in this study because it is a type of research method used to determine relationships between variables that are not correlated to several background variables. This allows researchers to conduct an observation on the same group of individuals over an extended period of time. The Minnesota Twin Family Study is a longitudinal study of twins. I believe this was chosen because it seeks to pinpoint the genetic and environmental impacts on the change of psychological traits over a period of time. Data collection was also used in this study. I believe this was chosen because the data was first collected at the beginning of the study and assembled throughout the extent of the study. The data collected by researchers indicate that the IQs of the adult monozygotic reared apart twins measured with various instruments in four independent studies link about 0.70, indicating that about 70% of the observed variation in IQ in this population can be ascribed to genetic variation. Researchers found that two-thirds of the observed variance of IQ can be drawn to genetic v...