Research Methods - Biological Pyschology Flashcards
What is correlation
A method used to assess the degree to which to co variables are related to
Pros of correlation
- correlational analysis allows us to look at the relationship between continuous variables and determine whether the relationship is significant
- it is a useful way to conduct an initial analysis on data, as if correlation is not strong then we can rule out a causal relationship and if the correlation is strong then further investigation is justified because there may be a causal link
Cons of correlation
- cannot prove causation as it does not show a cause and effect relationship as there has been no IV that has been deliberately altered
- it does not tell us the direction of the effect of the correlation
- there may be intervening variables that can explain why the covariables are linked
- the method used to measure either co variable may lack reliability or validity
What is a scatter diagram
A graph that shows the correlation between two co variables by plotting dots to represent each pair of scores
What is the correlation coefficient
A number between +1 to -1 which describes the correlation in a scatter graph
+1 is a perfect positive correlation
-1 is a perfect negative correlation
What inferential tests
Tests that enable us to study the relationship between two sets of data
Example of inferential test
Spearman’s rho
What does spearman’s rho test for
The relationship between co variables
Steps of spearman’s rho
Step 1:
State the hypothesis
Step 2:
Places scores A and B in a table from low to high
Rank the scores separately for A and B where 1 is the lowest score, if there are two scores that are the same add the ranks consecutive ranks of that score and divide it by 2
Calculate the difference (d) between rank a and b
Square each difference (d^2)
Add up all the squared differences (d^2)
Step 3: find the observed calculated value of rho
rho = 1- 6 x sum of d^2/ number of participants ( number of participants ^2 -100)
Step 5: find critical value of rho
Need to know:
- level of significance: 5% (0.05)
- n value (number of participants)
- kind of hypothesis
Step 6: state the conclusion
Levels of measurement
- nominal data
- ordinal data
- interval data
What is nominal data
- data in separate categories i
Types of brain scans
- CAT scans
- PET scans
- fMRI scans
What are CAT scans
Computerised tomography (CAT Scans) type of brain scans that use X rays and a computer to create detailed structural images of the inside of the body.
Three types of data
- nominal
- ordinal
- interval
Characteristics of nominal data
- data that is put in categories
- only gives little information as it only tells how many people are in each group
Characteristics of ordinal data
- it is data that put in order
- units of measurement are not equal
- does no tell us the difference between the 1st and 2nd and 4th and 5th
- tend to be subjective
Characteristics of interval data
- most complex measurement
- where data is measured using units of equal intervals