Correlation refers to the average relationship between two variables and the correlation coefficient is the measure of 1) the degree to which the two variables are related, and 2) the direction of that relationship. There are different types of correlation coefficients including Pearson product-moment correlation, point-biserial coefficient, spearman rho coefficient, and phi coefficient. The specific ...

A test of significance amounts to a question as to whether the effects observed in a sample reflect a true effect in the population from which the sample was drawn. To answer this question, we use a strategy. We assess the probability that the effect observed in the sample would have occurred by chance given ...

The mathematics behind regression makes certain assumptions and these assumptions must be met satisfactorily before it is possible to draw any conclusions about the population based upon the sample used for the regression. That is, the assumptions must be met in order to generate unbiased estimates of the coefficients such that on average, the coefficients derived from the sample ...

Experience sampling methods (aka diaries) are used to collect brief responses to questions about affect, cognitions, and behaviors 1 to many times per day over the course of some period of days. Given multiple data entry sessions, there in general 4 different schedules in which this can be accomplished: Interval-contingent reporting Signal-contingent reporting Event-contingent reporting ...

The limitations of retrospective reports We humans are susceptible to a remarkable range of perceptual illusions. We’ve all seen them. Here’s a particularly famous one. Looking at the two figures below, you’d swear that the vertical lines are bowed in the left-hand image and pinched inward in the right-hand image. In fact, all 4 lines ...

A vast amount of psychology related research consists of asking people about the past: how they felt, what they thought, what they did, and why they did it. The problem with this very common strategy is that human memory is notoriously flawed. It’s flaws and biases have been widely documented. Perhaps even worse and more insidious ...

A considerable body of evidence has shown that the order in which questions are asked can influence responses. For example, if a survey has a mix of open and close-ended questions, placing the closed-ended questions first can bias responses to subsequent open-ended questions toward those mentioned in the close-ended questions. More than 50 years ago researchers Herbert ...

One of the factors that often receives less attention than it deserves is sampling. When attempting to understand some phenomenon there is typically a population of some interest. A population is the group of individuals that we are ultimately attempting to learn something about.  All the people living in Pennsylvania, all patients with diabetes mellitus ...

There has recently been a somewhat of a crisis in Social Sciences research. When a group of researchers attempted to replicate many studies published over the years, including some rather famous ones, they found that many could not be replicated. The results of these studies were likely the result of chance.  When a study is ...

During World War II, the British Royal Air Force (RAF) had the idea of reinforcing their airplanes with heavy metal plating to increase the likelihood of surviving German attacks. But they couldn’t reinforce the whole plane because it would be too heavy. So they examined the planes returning to see where the planes had the ...