The determining factors for this are measures of resources that a parent can invest, the variable being the environment. The interaction of neighbouring individuals is a crucial factor in affecting the development of organisms in a community. ONOO- is implicated as a causative factor of cerebral disorders such as strokes and Alzheimer's disease . Other environmental factors governing formation social structure and constituent numbers are factors such as protection from predators. Species richness and functional diversity in a community are important factors in regulating ecosystem properties. Education was also an important factor with people of higher education level. Reductions in long hours might be a factor associated with increases in employment. Factors like age and the presence of children proved not to be significant when examined in isolation.