statistics back to basics

7/27/2019 Statistics Back to Basics

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Statistics

By Karan Dave


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Very basic..

Define population

-It is a set of all elements of interest in a

particular study

Define Sample

-A sample is a subset of population


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What information do we get from

mean, median & mode?

All 3 are measure of location

Mean

Median Mode


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Tricky ones

You are regional sales head of Pepsi. Which

measure of location you will choose to present

the last quarter sales of each drink under

Pepsi?

What is underlying difference between Mean

& Median?

What do you mean by Trimmed mean?


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What do you mean by Variability?

Range

Interquartile range

Interpret the followingOur DSO with different customers has a range

of 25 days, but we should not worry because

interquartile range is only 5 days.


7/19

What is the difference between

standard deviation and variation?

Very simple Sir, standard deviation is square

root of variance!!

Recruiter, Than 4 and 2 are different because

2 is square root of 4??

standard deviation is easier to interpret than

the variance because the standard deviation is

measured in the same units as data


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Whom will you give the bonus?

HR head/Sales head has to give bonus to 1

sales team out of 2 according to performance

of last 12 months.

Avg sales 250 units

Std 15 units

Avg Sales 350 units Std 25 units


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Coefficient of variation

1st team=(15/250)*100%=6%

2nd team=(25/350)*100%=7.1%


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When will mean be higher than

median?

Skewness

Positive/Right

Negative/Left Symmetric

What is the characteristic of symmetric curve?


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You are given a sales target and you

say this to your team

IF we work within 2 standard deviation we will

get X% of sales

What is the value of X?

Z score (Chebyshevs Theorm)(75,89,94-2,3,4)

Emperical rule(68,95,99.99-1,2,3)

What is the Z score of outlier?


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What is covariance?

It is a measure of the linear association

between two variables

Sxy=11

Sxy=99

Which is better?

It is unit biased


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What is correlation coefficient?

It is also used to measure the strength oflinear relationship but it is not unit biased.

How do you interpret Rxy=3?

How do you interpret Rxy=0.93?

Rxy indicates measure of linear association, notnecessarily causation

Meal price and food quality are positivelycorrelated but increasing the meal price will notcause quality to increase


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Regression

Coefficient of determination

Coefficient of correlation

Adjusted R Square Multiple R square


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Distributions

Out of 10 customers you visit for a sales deal,

you confirm 3 deals

Your target for this month is 3 deals and you

have already met 7 customers but could not

crack the deal.

Which statistical tool you would use to

determine your chances?


17/19

You are manager of Burger King,

Chennai

You know every hour 30 customers come to

your outlet in Chennai

30 mins left for closing time

Your financial head asks for todays sales on

phone, but still 30 mins to go and todays

performance may give you some incentive

You add sales of 12 customers to original

figure. How will you back this statistically?


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You are operations manager at

Walmart

You look after ware house function

You know that on an average it takes 15 mins

to laod a truck at each center

If emergency situation occurs you need to

load a truck at each center in 12 mins

How will you measure the feasibility of this?


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