To establish a useful understanding of development of the boy demands a systematic investigation about the development events. Different aspects from the development imply different patterns and causes from the change, so there is way no simple to summarize the development of the boy. Nevertheless, the answer of some questions on each subject can provide comparable information on diverse aspects of the evolutionary change. The following questions were suggested for this effect by Waters and his colleagues.
  • What it is developed?
  • What excellent aspects of the individual change in a period of time?
  • which are the type and speed of the development?
  • Which are the development mechanisms ?
  • What aspects of the experience and to do that the inheritance evolutionary change?
  • Hay normal individual differences in the pertinent changes in the development?

There are differences of population in this aspect of the development (for example, the differences in the development of the children and the children)?

The empirical investigation that tries to respond to these questions can follow a series of patterns. Initially, the investigation of observation in natural conditions can be necessary to develop a narrative that describes and defines an aspect of the change of development, such as changes in the reflected reactions in the first year. This type of work can be followed by the correlation studies, the information collection about the chronological age and some type of development, such as the development of the vocabulary, the correlation statistics can be used to change of state. This type of studies, the characteristics of the children to different ages. These methods can involve the longitudinal studies, in which a group of children becomes to examine in several occasions as they grow, or studies of cross section, in which groups of children of different ages put themselves on approval once and they are compared to each other, or can have a combination of these approaches. Some studies on the infantile development to examine the effects of the experience or the inheritance by means of the comparison of the characteristics of the different groups from children in a design necessarily nonrandom. Other studies can use randomized designs to compare the results of groups of children who receive the different interventions or educative treatments.