Define correlation
When 2 or more variables are measured in order to identify if there is a relationship between them
What is a correlation coefficient ?
- number between -1 & +1 that represents the direction and strength of the relationship between 2 variables
What is a case study ?
An in depth qualitative study on a individual/ institution
What is a advantage of case studies ?
- able to offer rich , detailed insights into behaviours that have more in depth explanations compared to close- ended , quantitative methods of collecting data such as questionnaires that are briefer
What’s a disadvantage of case studies ?
- small sample size causes it to be less representative of a wider population
- less generalisable
- lack external validity
Define positive correlation
This means that as one variable rises so does the other ( and likewise if one falls so does the other )
Correlation coefficient is roughly 0.75 close to +1
Define negative correlation
As one variable rises , the other one falls
Roughly -0.75
Define zero correlation
If the correlation coefficient is 0 then the two variables aren’t linked
Eg. Students heights and average test scores
Correlation coefficient is roughly 0.01
What is an advantage of correlational research ?
- does not involve controlling any variables you can do it when you couldn’t do a controlled experiment
- can give ideas for future research
- correlation can be used to test for reliability and validity
What are some limitations of correlational analysis ?
- can’t establish “cause and effect” relationships - it can only show that there’s a statistical link between variables
Variables can be closely correlated without changes in one causing changes in the other - a third variable could be involved, only s controlled experiment can show cause and effect relationships - care must be taken when interpreting correlation coefficients - high correlation coefficients could be down to chance
Define distributions
Graphs plotted to represent the average and spread of some characteristics of the population
What is a normal distribution ?
Symmetrical about the mean
This symmetry means that the mean , median and mode are all the same
What shape should a normal curve be ?
The curve is symmetrical - it’s shaped like a bell with its peak at the mean
What does the width of the curve depend on ?
Standard deviation
What is a skewed distribution ?
When there are scores that cluster together at either end of the data
What is a positive skew ?
- there is a cluster of scores at the lower end of the data set
- the curve has a rail on the right side of the peak - said to be skewed to the right
- mode is less than the median which is less than the mean
- eg. Reaction times , the number of children in a family , and income
In positively skewed distributions what is bigger mode, median or mean ?
Mode < median < mean
What is a negative skew data ?
- there are more scores at the higher end of the data set
- the tusk is in the left side of the peak - it is skewed to the left
- more is more than the median which is more than the mean
Mode > median > mean - negative skew is less common but an example is age at retirement
Linear correlation
A systematic relationship between Co-variables that is defined by a straight line
Scattergram
A graphical representation of the association/ correlation between 2 sets of scores
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Data Analysis and Graphs33
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Sampling36
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Fundamental Terms38
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Correlation20
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Types Of Experiments12
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Controls4
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Reliability & Validity25
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British Psychological Society Code Of Ethics14
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Self Report24
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Scientfifc Process10
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Content Analysis And Thematic Anaylysis9
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Types Of Data12
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Alternative Ways Of Getting Consent3
