Experimental design

• What are the two reasearch designs

  Observational and manipulative
• What type of research study is correlation

  Observational
• What type of research study is descrtiptive

  Observational
• What type of research sutdy is experimental

  Manipulative
• Describe an observational study

  It looks for patterns and associations. But cannot prove causation.
• Describe a manipulative study

  The conditions of the participants are manipulated.

  It tests both the cause and effect of the variables.

  It aims to prove causation.
• What are the main princciples of experimental design

  Control, randomization and repetition.
• What are the features of a good research question

  It must be clear and precise.
• Why would you choose an observational sutdy of a manipulative one

  The data is easier to collect.

  It is less likely to have unintended consequences.
• What type of data is often used for observational studies

  Categorical
• What is the downside to manipulative studdies

  The manipulations may be impossible or unethical to perform.
• What is reverse causation

  When the response variable affects the explanatory variable.
• What is a confounding variable

  This is something that affects both the explanatory and response variable.

  This means that the response and explanatory variables have no effect on each other.
• What often follows on from observational studies

  Manipulative studies
• Why do you use a control in studies

  It allows your experiment to be comparative and establish whether the difference is just a random change over time.

  It also removes the possibility of the placebo effect.
• Why do you need to be able to replicate results

  Because individuals vary
• What are the types of manipulative studies

  Randomised controlled trial [RCT].
• Describe a randomised controlled trial

  It uses hypothesis testing for causality and prediction.

  The generalizability of the results is said to be sample dependent.

  The question would be pharased as:

  Does the intervention work for this sample?
• What are the types of observational studies

  Meta-analysis of randomised controlled trials.

  Quasi-RCT known as clinical controlled trials.

  Case-control study.

  Cohort study.

  Cross sectional study.

  Simple case study known as a survey.
• What type of research design has the highest generalisation

  Meta analysis of randomised controlled trials
• What type of research design has the lowest amount of generalisation

  Single case study
• Define the generalizability of a study


  This describes whether it can be applied to different people such as the wider population.
• Describe a single case study

  It does not examine causality or effects.

  It has no generalizability as it looks at treating an individual.
• Describe a cross-sectional study

  It analyses the data in a population at a single point in time.

  It has limited generalizability and no causality.

  It aims to look for an association between two variables.
• What is the alternative name for a survet

  Cross-sectional study
• Describe a cohort study

  It looks for an association between the independent variable and a negative outcome, which is the dependent variable.

  It develops a causality hypothesis and so has some generalizability.
• Describe a case-control study

  It compares two sets of parameters in each group of subjects.

  It looks for an association between the parameters, meaning it has some generalisability.