Introduction Psychological research is often done by developing and testing theories. A theory on the other hand is a well established, principle which has been developed to give a reasonable explanation to some worldly phenomenon. Most theories arise out of repeated observations, testing and other scientific facts, laws and tested hypotheses. In most cases, deductive approach is used to generate specified predictions from other general theories. The process through which detailed predictions are drawn concerning the validity of a theory is the testing of hypothesis. Hypothesis A hypothesis is a specified concept about a certain concept which can be tested about the anticipation of the outcome in the study (DeCarvalho, 1991, 48). For instance, a research developed to study the relationship between study habits among students and examination anxiety could have a hypothesis that states, “The study is developed to evaluate the hypothesis that students who studied better experienced less anxiety for examinations”. The hypothesis explains what the researcher is expecting as the outcome unless it is explorative (Coon & Mitterer, 2011, p. 23). Therefore the first role of hypothesis is presenting the premise on which the psychological study is based on. A well developed hypothesis in psychology will hence be able to give the researcher the direction of the experiment or investigation. The investigator will know which kind of data to collect, the methods to evaluate and measure the data, how to interpret and draw conclusions. Therefore the hypothesis in psychological expereiemns has explanatory power. They also suggest to the researcher the expected association between the variables under investigation (Coon & Mitterer, 2011, p. 29). The hypothesis are required to be testable and aligned to the current pool of knowledge about certain concepts and factors. The hypothesis also gives the reader a prelude of an experiment and therefore good hypothesis for psychological study should be simple and concise. A hypothesis provides the psychologist with an uncertain explanation of an observable fact therefore sparking a feeling of curiosity and therefore inspires and facilitates expansion of knowledge in that sector. A hypothesis also gives the investigator a relational statement which can be tested by scientific methods and therefore helps to determine the type of study method that will be used for investigations. As the method determines the data collected, hypothesis also guides the reporting of the findings and making conclusions (DeCarvalho, 1991, 48). This is because, the researcher seeks to accept or reject the hypothesis. And this is often the goal of the research. In psychological studies, hypotheses are normally drawn from the existing knowledge and theories. As such hypotheses in this field function as the working instrument of certain theories that need to be proven or need more knowledge in terms of literature or findings (DeCarvalho, 1991, 48). Psychology Psychology is described as the science of mental wellbeing and deals with both the status and the functioning. As a science, psychology is constituted by two essential principles (Hand 2004, p. 34). The first is that there has to be measurement. Hypothesis states the variables to be measured as a second role. This role is very important b