What are the allocation methods used in independent samples experiments? The allocation method simply refers to how the researchers decide who receives what treatment in an experiment. There are two ways to allocate participants: a) Randomly b) Selectively Random allocation is when the researchers divide the participants and allocate them to certain groups using a random method. For instance, in an …
What are the design types in experiments?
Choosing the best research design for your experiment is an important part of the planning process. When conducting an experiment for the IB Psychology IA, you must think very carefully about which design is best for your purposes. Experimental Designs (MP, IS, RM) There are three design types of experiments: Independent Samples Repeated Measures Matched Pairs Independent Samples is when the …
What is a “controlled variable?”
A controlled variable is a variable that’s kept constant between the conditions of the experiment so that the only difference between the groups is the independent variable. Imagine you’re doing an experiment on yourself to see if drinking coffee in the morning gives you energy. On Monday you wake up, do yoga and then have a cup of coffee. At …
Stating an Aim Clearly
How is the aim of an experiment stated? Being able to clearly state the aim of an experiment, or any study, is important for when you want to clearly describe a study. It is also a key part of the internal assessment. Since the purpose (or aim) of conducting a “true” laboratory experiment is to investigate a cause and effect relationship between …
Operational DefinitionsHow to operationally define IVs and DVs
Updated May 2020 Operational definitions became important in Psychology when psychologists wanted to establish that psychological experimentation is truly scientific in nature. In this blog post, we’ll look at exactly what is an operational definition is and how to do it. This is a common error in IB Psychology IAs. Hopefully after reading this post, students will be able to …
Hypotheses
Updated June 2020 Writing good hypotheses in IB Psychology IAs is something many students find challenging. After moderating another 175+ IA’s this year I could see some common errors students were making. This post hopes to give a clear explanation with examples to help with this tricky task. Null and Alternative Hypotheses Null Hypothesis (H0) The term “null” means having …
Single and Double Blind Designs
How are single blind and double-blind techniques used in experiments? Before understanding about single and double-blind techniques, it is important that you understand the amazing power of the placebo effect. This is an interesting film about placebos and their effect. [youtube https://www.youtube.com/watch?v=yfRVCaA5o18&w=560&h=315] Single Blind: A single-blind design is when the participant doesn’t know if they are in the “treatment group” or the “control …
Confounding Variables
Sometimes factors other than the IV may influence the DV in an experiment. These unwanted influences are called confounding variables. In laboratory experiments, researchers attempt to minimize their influence by carefully designing their experiment so all conditions are exactly the same – the only thing that’s different is the independent variable. Here are some confounding variables that you need to …
Independent and Dependent Variables
What are independent, dependent variables? The DV is what is being measured. It is the effect in other words. The IV is what is being manipulated by the researcher. In other words, it is the factor that changes in the different conditions of the experiment. The aim of an experiment, therefore, is usually to investigate the effect of the IV on the DV. Take this …
The Experimental Method
What is an experiment? By far the most common research method used in psychology is the experimental method, so we’ll start here for our introduction into research methods unit. You are also going to research, plan, design, conduct and report about your own experiment idea. A study is an experiment when the relationship between two variables is investigated. A variable …