# Glossary

I’m trying out this glossary thing. It’s very nascent, but imagine it would contain all the technical terms I use. Do let me know if it’s helpful! 🙂

2×2 Design – a 2×2 design is one of the classics of psychological experimentation. The basic research is about correlation or prediction, and involves one predicting variable (or independent variable) and an outcome. The next step is looking at two predicting variables and how they affect the outcome. For example, let’s say you want to know how the number of crayons and the presence of art on the walls influence the child’s production of drawings. In a 2×2 design, you take these two factors and manipulate them. For instance, you can give some of the children 3 crayons and some of the children 24 crayons. You can also sit some of the kids in a room with no art on the walls and some of the kids in a room with lots of art on the walls. If you cross these two you get a 2×2 design, with 4 groups: group A would have 3 crayons and no art on the walls; group B would have 3 crayons and lots of art on the walls; group C would have 24 crayons and no art on the walls; and group D would have 24 crayons and lots of art on the walls. If you count the number of drawings each of the groups produced, you can examine the effects of each of the factors, but you can also look at the interaction between the two factors.

Right now, I can only find one study that used a 2×2 design (which I talked about in the blog):

Meta-analysis – A study of studies. Basically, the scientist collects published studies and runs statistics on all the data that was used in all the studies. There are certain limitations to this method, but it’s a powerful tool because it allows us to see whether a certain effect is consistent across studies. You can also divide the studies along certain factors (for instance, what country were they conducted, the age of the children in the sample, etc.) and see if these factors influence the results.

Here are some examples of meta-analyses:

Random Assignment – This is when you assign participants in your study into groups. The groups differ along what you are trying to study. For instance, if you want to study the effect of colour on mood, you would assign your participants randomly (that is, not based on any of their traits such as age, gender, or personality) into three rooms: the blue room, the red room, and the green room. Randomly assigning people to the different groups means that the groups should be equal on other factors (such as age, gender, and personality), and, therefore, you don’t really need to worry about these other factors influencing your findings. You would then measure your outcome variable (mood), and if, for instance, people who have spent an hour in the green room are happier than people who have spent an hour in the blue room, you have evidence to support the idea that colour influences mood.

Here are some excellent studies that have used random assignment, and are therefore awesome (generally speaking):

Reliability – When something is reliable it works in the same way for a long(ish) period of time. In psychological testing, reliability is the tendency of people to get similar scores on the test. Think about a personality test, and assume that personality is a stable trait (i.e., we don’t change our personality from day to day). A good personality test would provide us with the same results regardless of when and how many times we take it. So, to test for reliability, researchers typically have participants do the same test twice, with a certain period of time in between. If the scores are similar between the first time you take the test and the second time you take the test, the researchers conclude the test is reliable.