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dispersion and distributions - Coggle Diagram
dispersion and distributions
standard deviation
the larger the dispersion, the greater the deviation
a large deviation suggest that not all ppts were affected by the IV in the same way. there may be a few anomalous results
a single value that tells us how far scores deviate (move away) from the mean
a low deviation value reflects the fact that the data is tightly clustered around the mean, implies ppts all responded in a similar way
mean
more representative of the data as a whole
mean is easily distorted by extreme values
median
not affected by extreme scores and easy to calculate
it is less sensitive than the mean as the actual values of higher and lower numbers are ignored - extreme values may be important
range
unrepresentative of the data set as a whole, as it only takes into account the two most extreme values
always +1 to calculate
distributions
skewed distribution = a spread of frequency data that is not symmetrical, where the data clusters to one end
positive (going forward) skew = a type of frequency distribution in which the long tail is on the right side of the peak
normal distributions = a symmetrical spread of frequency data that forms a bell-shaped pattern. the mean, median and mode are all located at the highest peak
negative (going backwards) skew = a type of frequency distribution in which the long tail is on the left side of the peak