Like everything else in life, not all research is excellent. Research may vary in quality. The most critical quality of research is its accuracy. What makes research valuable is if it is correct.

Now, what makes research accurate? What makes them can explain this world and also can predict what happens next? The answer is the method.

Research is a part of scientific activity. What does scientific mean? Scientific means:

First, the researcher has to provide reason and evidence for their claim. The reason should be logic and coherence. Data should merely be based on the fact that observable for everybody. Claim without reason and evidence are worthless.

Second, anybody should able to test the researcher’s claim by replicating their method of research. This replication process makes sure that they are not miscalculating or even manipulating their data. Research that fails the replication process by other scientists is also worthless.

Third, research should be testable. Research conclusion has able to test against any data that come later. If newer data prove that the conclusion is wrong, then this research is defunct.

Fourth, the research claim must be falsifiable. Maybe this is the weirdest thing about the scientific method. Falsifiable means that there are ways to prove the research claim is wrong. If it is not falsifiable, it is dogma or doctrine. By definition, dogma or doctrine is not questionable. Research is not dogma nor doctrine.

Therefore, the most accurate research is the most discipline one, the more rigorous one that follows the scientific method. The research that provides the most logical and coherent reasoning is the best one. The research that provides a very lot of data is the best one. Usually, research that provides 10,000 data samples better than other research that provides 100 data samples. The research that already passes the replication test by many other researchers better than research that has not. The research that passes newer and newer data is better.

The hierarchy of evidence also classifies research. Bigger data nearly always better, but not always. The researcher can arrange evidence with many methods.

The highest quality of research is called a meta-analytic or systematic review. This research is not gathering data directly, but gathering data from many types of research. So this is the research about previous researches.

The second best is Randomized Controlled Trials or RCT. This is a research conducted by randomly dividing the sample into two groups: a treatment group and a control group. Both groups have a very similar character. The intervention factor that research interest to observe is applied to the treatment group while the control group is not intervened at all. If the actual effect observed by researcher happens in the treatment group, the researcher can safely say that the intervention that makes it happen, not some other unobservable factors.

The third level is the cohort study. This method uses samples a group of people who share a particular characteristic, typically those who experienced a common event in a selected period, such as birth or graduation, performing a cross-section at intervals through time.

The fourth level is the case-control study. This is a study that compares subjects who have an outcome of interest (cases) with subjects who do not have the outcome (controls). The researcher looks back retrospectively to compare how factor is present in each group to determine the relationship between the factor and the outcome. Case-control studies are observational because no intervention is attempted, and no attempt is made to alter the course of the effect. The goal is to retrospectively determine the exposure to the factor of interest from each of the two groups of individuals: cases and controls.

The fifth is a cross-sectional study. This is a type of observational study that analyzes data from a population, or a representative subset, at a specific point in time, not period. Therefore the quality below cohort study. Case report or case series is research that only observes a or some cases. Therefore the generalization is weak. Expert opinion is solely based on one professor or a single expert opinion. Therefore this is the weakest evidence available.

The Genesis of Theory and Competition Among Them

From facts and data, one scientist or thinker may generate a theory. Why do scientists ambition is to contribute a theory? Because, the highest form of scientific thinking is a theory. That is the explanation and prediction of a phenomenon. Good theory satisfy our curiosity about the question of what causes this and what will happen after this. So the theory is a set of causal explanations about a phenomenon. Usually, in the scientific world, a phenomenon drives many competing theories to explain and to predict. Now, how to evaluate competing theories. Here is the answer: