Distributions Flashcards
distribution in statistics
A set of data values or scores organised in a way which enables the shape of the data to be seen/’eyeballed’
frequency of normal distribution
perfectly symmetrical around its average value, the ‘mean’
mean of normal distribution
The mean splits the area under the distribution curve in half
differences between the mean, median and mode of normal distribution
equal
description of physical normal distribution curve
smooth and symetrical
non-normal distributions mean median and mods
mean, median and mode are different
types of non-normal distributions
skew and kurtosis
positive skew
mean and median > mode
negative skew
mean and median < mode
how to visually work out the type of skew
if flipped round it look like a “p” its positively skewed
kurtosis
a steep curve with short fat tails
difference between normal distribution and kurtosis
kurtosis = steep (leptokurtic) , normal = shallow (platykurtic)
mesokurtic
no skew and neutral distribution - like a bell
poisson distribution
he number of times an event happens in a period, where the event is independent of the number of times it happened in the previous periods.
Biomodal distributions
a mixture of two distributions with different means eg height
