Notesale: Turn your study into money

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FORMULAE + KEY INFORMATION
Median, IQR, LQ, UQ, Fences…
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Median and quartiles are to be found manually
Lower Inner Fence: LQ – 1
...
5*IQR
Lower Outer Fence: LQ – 3*IQR
Upper Outer Fence: UQ + 3*IQR

Any data within lower fences is a
possible outlier (*)
Any data outside the outer fences is
a probable outlier (°)

Standard Deviation & Mean for sets of data
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Midpoint of a range: (minimum + maximum)/2
Calculator Steps:
1
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[2] STAT
3
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Enter the midpoint and frequency
5
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SHIFT
7
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[4] VAR
9
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g
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g
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g
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n=100+
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Proportion will be 80 for 80% not 0
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e
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𝟎𝟓𝑸) what is Q when AC=12
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𝟎𝟓𝑸) =

Logarithm (𝑙𝑛 is log 𝑒
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2 key points:
 Interesting slope – never levels off just gets less and less steep
 Useful for solving a number of equations
If 𝑙𝑛 is being taken away from 𝑙𝑛 – divide them e
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75 ln −5 ln = 15𝑙𝑛
If 𝑙𝑛 is being added to 𝑙𝑛 – multiply them e
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5 ln +5 ln = 25𝑙𝑛
Example:
𝑷 = 𝟏𝟓𝒍𝒏(𝟕𝟓𝟎𝑩 + 𝟏𝟓𝟎𝟎) − 𝟏𝟓𝟎 what is B when P=0?
𝟎 = 𝟏𝟓×𝒍𝒏(𝟕𝟓𝟎𝑩 + 𝟏𝟓𝟎𝟎) − 𝟏𝟓𝟎

FORMULAE + KEY INFORMATION
Correlation and Regression
 Correlation and regression analyses are used to study the relationship between variables
 Explanatory variable = independent variable (variable you change)
 Response variable = dependent variable (variable you measure)
 Explanatory variable goes on the x-axis
 Response variable goes on the y-axis
Correlation
 Measures the strength and direction of a linear relationship between variables
 Correlation coefficient (1 to -1) – measures the strength of said relationship
 Close to 1: strong positive relationship
 Close to -1: strong negative relationship
 Close to 0: weak linear relationship
 0: no relationship
Regression Line
 Considered to be the line of “best fit” – line that minimises the sum of squared errors
 Calculating a regression line equation: apply the equation of linear lines: 𝑦 = 𝑎 + 𝑏𝑥
 Fitting a regression line: using the equation produced, calculate a number of points to
outline the position of the line

Modelling
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Model is a simplified representation of reality, created for a specific purpose

Variables
 Decision Variable – variable whose value can be chosen (“under management control”) e
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number of staff being on till at a time, floor area taken up by checkouts…

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Environmental Variable – variable whose value is out of the control of those making the model and is
“fixed” to a degree e
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total land available for development, customer arrival patterns, customer
budget patterns…

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Output Variable – variable whose value depends on other variables in the model e
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total time a
customer spends at a checkout, number of new customers gained(loyalty card records), total sales,
staffing costs…

Approaches to Tackling a Problem
 Solve – carry out a thorough investigation
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1
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3

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