Distributions Flashcards
What are the features of a normal distribution graph?
- symmetrical from both sides
- mean, median and mode are identical or very similar
In a normal distribution graph, what is the number of 1 standard deviation above and below the average?
68.2
In a normal distribution graph, what is the number for 2 standard deviations above and below the average?
95.4
What are the features of a negatively skewed distribution?
- The lump is to the right
- Mean is the lowest and mode is the highest
What are the features of positively skewed distribution?
- Lump is to the left
- Mode is the lowest, mean is the highest
What is happening to cause a negative skew and what might a psychologist do to make the data more normally distributed?
- People have scored well
- The psychologist needs to make the test hard which will cause the lump to move to the centre as people will do less well
What is happening to cause a positive skew and what might a psychologist do to make the data more normally distributed?
- People have scored badly
- The psychologist needs to make the test easier which will cause the lump to move to the centre as people will do better
If asked about how to make a graph normally distributed what should your first point be?
‘Adjust the difficulty of the test’
And then specifically say make the test harder/easier.
When comparing data on a table about how the distributions differ what must your first point be?
‘Group A differs from Group B as they have different distributions’
Then go on to say if they are normal/positive/negative and how you know that e.g normal if averages are the same or positive/negative depending on the order of these averages.
What is the outside percentage of the two standard deviations? What would one side of that outside be?
Outside percentage = 4.6 (100-95.4)
One side of outside percentage = 2.3 (4.6/2)
