PSYC1040 Week 5 Flashcards

Variability, situational factors and normal distribution

1
Q

Variability

A
  • most studies involve taking measures of a sample of participants drawn from a population
  • but, any sample distribution will likely differ from the population distribution, just by change, so individual studies will not be perfectly reliable
  • in particular, each sample mean will differ from the population mean
  • assuming the population distributions is normal, we can estimate how much a sample mean will likely differ from a population mean, if we know two things:
    ~ the n.o of participants in a sample
    ~ the amount of variability in the population (SD).
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2
Q

Stable individual differences

A
  • basically, traits of participants
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3
Q

Situational factors

A
  • e.g background noise during a testing session, participants experiences on the day of testing and soon
  • to quantify the extremity of a score, we can say how many SD it lies from the mean
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4
Q

The normal distribution - characteristics

A
  • many variables are normally distributed e.g height, IQ, personality measures, memory performance, symptom severity etc
  • when variation is due to many separate random influences, it will tend to follow a normal curve
  • many inferential statistical tests are therefore based on the properties of a normal distribution
  • in particular, they’re based on the mapping of z-scores to percentiles in a normal distribution
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