Research and Statistics Flashcards
What are the 4 categories of Statistics?
- Nominal
- Ordinal
- Interval
- Ratio
Define Population in relation to research
Complete set of events in which you are interested.
Note that a population is not always a group of people. It can also be a group of stimuli.
What is a sample?
A smaller group of the population
What is a Random Sample?
Participants selected at complete random in an arbitrary way
What is an Independent Variable (IV)?
Variable manipulated by the
experimenter. Variable you want to test.
What is a Dependent Variable (DV)?
Variable that you measure. This variable is dependent on the independent variable.
What are Confounding Variables?
Variables that have a systematic effect on the dependent variable, but in which you are not interested. It is very important to remove confounding variables from your study.
What are Random Variables?
Variable that has a random effect on the dependent variable and which you are not interested. These variables result in “noise” in the data and should be limited as much as possible.
What is an example of a Non-random assignment in between participants design
If participants can choose whether they are in the alcohol condition, then bad drivers may be more often in that condition.
How can History affect research?
Events that occur between different tests may affect the outcome of the tests. (E.g., researcher investigates effect of exercise programme on health, but during the programme, participants don’t walk outside because of snow and ice.)
How can Maturation affect research?
Participants change over time. (E.g., Children’s cognitive performance is higher before than after a training programme. However, children have also become older, resulting in higher cognitive performance.)
Explain:
Order/testing effects
Performance on second test is affected by the first. Due to practice effects with the test, participants may score higher on 2nd than 1st test, and due to fatigue they may score lower on the 2nd test.
What is a Placebo effect?
Participants perform better because they believe that the manipulation should make them perform better.
What is Regression towards the mean?
When you select participants on the basis of their very high/low scores, they tend to have a lower/higher score when you test them a second time, because their initial low score is likely to be partly due to chance.
What is Mortality?
Performance improves at the 2nd test because the worst participants have dropped out (sometimes because they died, but often because they did not want to take part in the 2nd test).
