S1 Statistics Revision - Chapter 4 Notes

Chapter 4 - Methods of summarising data (dispersion)

HideShow resource information
Preview of S1 Statistics Revision - Chapter 4 Notes

First 195 words of the document:

AS Statistics Revision
Statistics 1 ­ Chapter 4
Methods of summarising data (dispersion)
Key points to remember
Range = the value obtained when the smallest observation in
a
data set is subtracted from the largest one.
Interquartile range (IQR) = the value obtained when the
lower
quartile is subtracted from the upper quartile.
IQR = Q3 ­ Q1
Outlier = an extreme value which does not fit into the main
body
of the data. Any rules to identify outliers will be specified in
the
S1 question paper. The usual equation tends to be either
For the lower outlier limit = LQ ­ (1.5 x IQR)
For the upper outlier limit = UQ + (1.5 x IQR)
Variance = the variance of a population of observations. This
is
the standard deviation squared.
i.e. (fx² ÷ n) x²
Standard deviation = (fx² ÷ n) x²
Skewness = an indicator of the shape of a distribution.
Symmetrical: mode = median = mean
Positive Skew: mode < median < mean
or Q2 ­ Q1 < Q3 ­ Q2
Negative Skew: mean < median < mode
or Q2 ­ Q1 > Q3 ­ Q2

Comments

No comments have yet been made

Similar Statistics resources:

See all Statistics resources »See all resources »