EDEXCEL A LEVEL STATISTICS PAPER 3 2026
KEY STATISTICAL METHODS AND CONCEPTS
REVISION PACK A+
◉ coding - inverse function. Answer: means it is the exact inverse
function e.g if the x was formed from 2y+4 you would do x-4 /2 to
get x
however for standard deviation it is slightly different
-if standard deviation =b was formed by 3d+8 to get the d you would
just divide by 3 and not account for subtracting the 8. - However IT
IS ALWAYS POSITIVE VALUE SO IF WORKING BACKWARDS IT
COULD BE NEGATIVE OR POSITIVE SO YOU WOULD NEED MEAN
INFORMATION TO SOLVE.
◉ variance. Answer: standard deviation squared
◉ binomial PD. Answer: probability of n successful
◉ binomial CD. Answer: probability of 0-n successful cumulative
,◉ in binomial distribution for each random variable what must
there be. Answer: - independent of each other
- fixed number of trials
- 2 outcomes
- fixed probability
◉ how to find which to put on x axis. Answer: x always on top or left
of graph
◉ uniform distribution. Answer: probability of eachh event exactly
same
◉ what is trace in statistics. Answer: a specific value which is small
◉ comparing box plots. Answer: - Compare Medians
- Compare Range (IQR)
- Compare Skew
- Put comparison into context
◉ histograms what to know. Answer: class width * frequency
density = frequency
might need to use ratios
,class width shown to you
might need to see that if a certain area represents a certain
frequency in a certain ratio , how you can apply this ratio to the
others
need to practice this with pp
◉ cumulative frequency tables to remember. Answer: - keep a
running total
- plot against upper boundaries
- make a smooth shaped s curve
◉ unimodal data. Answer: data with one mode
◉ uniform data. Answer: no mode / data is symmetrical
◉ bimodal data. Answer: A histogram will have two peaks as the
data has two modes.
- peaks do not have to be equal
, ◉ how to interpolate data e.g find the 17th value. Answer: go across
each frequency and when you find the area upon which the 17th
value lies, and lets say the first category contained 10 and the next
12,
- you would do 17-10 =7 to get remainder of 7 , then do 7/12 * class
width = x
- then you would add x to the starting value in the class width and
that is answer
◉ traps you could fall for interpolation. Answer: - nearest minute -
make sure to get correct class width for this
◉ mean. Answer: the arithmetic average of a distribution, obtained
by adding the scores and then dividing by the number of scores
- pros uses every data item
- cons affected by extreme values
◉ median. Answer: the middle score in a distribution; half the scores
are above it and half are below it
pros - unaffected by extreme values
- could still calculate if couple data items missing
KEY STATISTICAL METHODS AND CONCEPTS
REVISION PACK A+
◉ coding - inverse function. Answer: means it is the exact inverse
function e.g if the x was formed from 2y+4 you would do x-4 /2 to
get x
however for standard deviation it is slightly different
-if standard deviation =b was formed by 3d+8 to get the d you would
just divide by 3 and not account for subtracting the 8. - However IT
IS ALWAYS POSITIVE VALUE SO IF WORKING BACKWARDS IT
COULD BE NEGATIVE OR POSITIVE SO YOU WOULD NEED MEAN
INFORMATION TO SOLVE.
◉ variance. Answer: standard deviation squared
◉ binomial PD. Answer: probability of n successful
◉ binomial CD. Answer: probability of 0-n successful cumulative
,◉ in binomial distribution for each random variable what must
there be. Answer: - independent of each other
- fixed number of trials
- 2 outcomes
- fixed probability
◉ how to find which to put on x axis. Answer: x always on top or left
of graph
◉ uniform distribution. Answer: probability of eachh event exactly
same
◉ what is trace in statistics. Answer: a specific value which is small
◉ comparing box plots. Answer: - Compare Medians
- Compare Range (IQR)
- Compare Skew
- Put comparison into context
◉ histograms what to know. Answer: class width * frequency
density = frequency
might need to use ratios
,class width shown to you
might need to see that if a certain area represents a certain
frequency in a certain ratio , how you can apply this ratio to the
others
need to practice this with pp
◉ cumulative frequency tables to remember. Answer: - keep a
running total
- plot against upper boundaries
- make a smooth shaped s curve
◉ unimodal data. Answer: data with one mode
◉ uniform data. Answer: no mode / data is symmetrical
◉ bimodal data. Answer: A histogram will have two peaks as the
data has two modes.
- peaks do not have to be equal
, ◉ how to interpolate data e.g find the 17th value. Answer: go across
each frequency and when you find the area upon which the 17th
value lies, and lets say the first category contained 10 and the next
12,
- you would do 17-10 =7 to get remainder of 7 , then do 7/12 * class
width = x
- then you would add x to the starting value in the class width and
that is answer
◉ traps you could fall for interpolation. Answer: - nearest minute -
make sure to get correct class width for this
◉ mean. Answer: the arithmetic average of a distribution, obtained
by adding the scores and then dividing by the number of scores
- pros uses every data item
- cons affected by extreme values
◉ median. Answer: the middle score in a distribution; half the scores
are above it and half are below it
pros - unaffected by extreme values
- could still calculate if couple data items missing
