When you are doing research on a given populationto find out how people change with time, three research methods can be used. These methods include the following, longitudinaldesigns, cross-sectional designs and sequential designs (Creasey, 2006).
A longitudinal design is a type of research study where a given sample of the population is consideredat intervalsto examine any changes or development. For example, to conduct a longitudinal design research, we may start with ten years old, check with them after every ten yearsto examine any changes (Brown & Cozby, 2002).
Cross-sectional designs can be defined as a type of research study thatreviewsa sampled groupsalong a developmental in a study to establish how a development or change influence an analysis variable. In this kind of the investigation study, instead of taking one sample of the group of people and studying them for anextensive period, somegroups of people are considered, and study is done at once. In this case, a group of ten years, twenty years and so on is selected at once. Cross-sectional design research saves time since all the examination is done at once, not over an extended period of time (Creasey, 2006).
The sequentialdesign is a type of research study which combines both the longitudinal design and cross-sectional. It is also knownas across-sequential design. The research method studies several different age cohorts over a given period. With longitudinal design research method, one group of a given populations is investigatedfor a long time. With cross-sectional design, a whole group of thepopulation is considered right now. With sequential, a whole bunch of groups is considered over time (Creasey, 2006).
All the three research methods have both advantages and limitation. The longitudinal design has one main advantage in that individual differences are noted and recorded, and if there are any changes occurringamong the individuals, it can be quicklyobserved. The cross-sectional design has one chief merit in that research study can be completed within a very short time, and it saves time. Also, the sample picked for thestudy is a real representation of the whole population. Lastly, thesequential design has the advantages of the research methods in that it can provide information over a short period since several groups are being studied over a given period (Creasey, 2006).
Some of thelimitation of the above research methods include the following: One of the limitations of the longitudinal design is that it can be considered as quasi-experiment, and it is hard to validate the study parameters. On the other hand, cross-sectional design limitation is that some assumptions have to be made when conducting the study, and this may not provide an accurate picture of the whole population (Creasey, 2006).
Systematic observation is a process of setting a research study to eliminate or reduces bias. It refers to a set procedure use during thecollection of research data (Ong & Dulmen, 2007). Self-reports can be definedas a methodology and is usually used in behavioral science to collect data. It is using a set of questionnaires to gather data from the subjects of the study (Jackson, 2008). Clinical methods refer to research methods that areemployed in the field of clinical medicine to collect data for aresearch study. On the other hand, ethnography refers to a type of the investigation method that is used to record human cultures and provide a detailed description of everyday life and practice (Ong & Dulmen, 2007).
Brown, K. W., & Cozby, P. C. (2002). Research methods in human development. Mountain View, Calif. : Mayfield Pub.
Creasey, G. (2006). Research methods in lifespan development. Boston: Pearson/A & B.
Jackson, S. L. (2008). Research methods: a modular approach. Belmont, CA: Thomson Wadsworth.
Ong, A. D., & Dulmen, M. H. (2007). Oxford handbook of methods in positive psychology.Oxford; New York: Oxford University Press.