The Beginnings

Observing Changes over Time

Patterns of Developmental Growth

Observation Scientific observation is a method of testing a hypothesis by unobtrusively watching and recording participants’ behavior in a systematic objective manner, in a natural setting, in a laboratory or in a searches of archival data.

The Experiment Experiment : a research method in which the researcher tries to determine the cause-and-effect relationships between two variables by manipulating one (called the independent variable ) and then observing and recording the resulting changes in the other (called the dependent variable ).

The Experiment independent variable: the variable that is introduced to see what effect it has on the dependent variable (Also called experimental variable ) dependent variable: the variable in an experiment that may change as a result of whatever new condition or situation the experimenter ads. In other words, the dependent variable depends on the independent variable.

The Experiment experimental group: is a group of participants in a research study who experience some special treatment or condition (the independent variable). control group: a group of participants in a research study who are similar to the experimental group in all relevant ways but they do not experience the experimental condition (the independent variable).

Applying the Scientific Method

Cross-Sectional Research Cross-sectional research is a research design that compares groups of people who differ in age but are similar in other important characteristics.

Longitudinal Research Longitudinal research is a research design in which the same individuals are followed over time and their development is repeatedly assessed. 1 2 3

Some Findings from Longitudinal Research

Applying the Scientific Method