External validity is about the generalizability of the results to different populations, settings, periods, treatment variables, and measurement variables. Then, threats to external validity are the conditions that limit this generalization of the results. Since external validity specifies conditions under…
Threats to internal validity are characteristics of research design that jeopardize our ability to interpret and make appropriate inferences. That is, it is an evaluation of the research design to provide causal inference. But to infer causality we must be…
We are very well aware of type I and type II errors in statistics. However, there is the error of the third kind or type III error that is more conceptual than type I and type II. It results from…
Empirical research is often conducted to establish evidence of a phenomenon or relationship, to examine and evaluate causal relationships, or to provide an explanation of how, why, and under what conditions a causal relationship exists. The purpose of the research…
Reliability, fundamentally, concerns the extent to which a measure, an experiment, or test yields the same results on repeated trials. However, the measurement of any phenomenon invariably contains a certain amount of chance error. Even repeated measures of the same…
Reliability coefficients measure the consistency of a measurement scale. That is, they answer the question — how consistent is the scale or instrument when multiple observations are taken when the true score is unchanged? The reliability coefficient quantifies the precision…
Now that we have talked about probability sampling, let’s focus on non-probability sampling in research. We saw that we need a sampling frame whenever we want to go for a probability sampling technique. But many times, a sampling frame is…
Although there are millions of shoppers during the holiday season, only a few thousand of them are actually sampled to determine their shopping habits. An obvious question is why only a few thousands? Well, the simple answer is time and…
There are four basic types of scales of measurement – nominal, ordinal, interval, and ratio. Since each scale is better suited to specific types of variables, it limits or enables us to perform specific statistical operations or tests. Let’s look…
Let’s discuss a simple situation in which we have two variables to understand regression analysis and what it means, and how to interpret the outcomes of regression analysis. In other blog posts, we discuss how to do a simple regression.…
