PSYC1040 Week 6

Question 1

Why are many things normally distributed? Variation will tend to follow a normal curve when:

Answer 1

• the variable’s state is affected by many influences
• the influences are separated from each other (not associated)
• the range of possible variation is unlimited
• stronger violations of these conditions make a distribution less normal and conditions are described more precisely by the ‘central limit theorem’

Question 2

More properties of ‘true’ normal distributions: In a mathematically defined normal curve ~

Answer 2

• mean, median and mode are identical
• curve is symmetrical around the centre
• traits are infinitely long
• tails approach zero while never reaching it

Question 3

More properties of ‘true’ normal distributions: variation in singe variables ~

Answer 3

• how it informs our estimates e.g probability
• ideas about variation and its causes
• describing variation with graphs, tables and descriptive statistics

Question 4

More properties of ‘true’ normal distributions: association between pairs of variables ~

Answer 4

• improving our estimates by bringing in more variables
• associations and cause and effect judgements (causal inferences)
• describing associations: graphs, tables and statistics