Part 3 Flashcards
inferential statistics
making inferences from distributions
the normal distribution
describes a common probability distribution of values of a continuous variable around the mean
vertical axis=
frequency of values
horizontal axis=
continuous values (scores total)
properties of the normal distribution:
symmetric, unimodal, mean mode and median are the same value and are equal to the centre of distribution
the specific shape of the curve depends on :
mean (location of peak on x-axis), standard deviation (how spread out the curve is)
standardization of normal distribution
allows comparison of relative standing for different scales, standardize by converting raw score deviations into standard deviation units (z-scores)
properties of standard normal distribution
- the cumulative area (read left to right) is close to zero for z-scores close to -3.49
- the cumulative area increases as the z-scores increases
- the cumulative area for z=0 is 0.50
- the cumulative area is close to 1 for close to z=3.49
z-score correlates directly to:
standard of deviation from the mean
properties of probability with continuous variables:
limitless number of possible values for this variable, probability of event falling in an interval, described as the area under the curve for a specified interval
properties of probability with discrete variables:
can take on limited number of possible values, probability of specific outcomes
importance of probability in everyday life:
- probability judgments
- knowledge of probability helps us understand human limitations
- consumer judgment
what are the types of probabilities?
subjective probability, analytic or theoretical probability, expected relative frequency (empirical) probability
probability experiment
an action, or trial, through which specific results are obtained
outcome
the result of a single trial in a probability experiment