Tags: AVERAGEX

Compute an average for the same day in the past 3 years

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Assume a simple two column dataset with dates in column A and numbers in column B. The dates in column A are from January 1, 2013 to December 31, 2016 and numbers in column B are for the period January 1, 2013 to December 31, 2015 (there are no numbers for January 1, 2016 to December 31, 2016).

The objective is to "Compute an average for each day of calendar year 2016. The average should be for the occurrence of that day in the previous 3 years". Here's an example:

1. January 1, 2016 was a Friday (the first Friday of 2016) and is in cell A1097
2. In cell B1097, the average should be computed as: Average of the "First Friday of each of the previous 3 years"
3. January 8, 2016 was a Friday (the second Friday of 2016) and is in cell A1104
4. In cell B1104, the average should be computed as: Average of the "Second Friday of each of the previous 3 years"

I have solved this problem with the help of the PowerPivot. You may refer to my solution in this workbook.

Data slicing and analysis with the Power Pivot

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Visualise an MS Excel file with two worksheets:

  1. Employee headcount – a multi column dataset with information such as Employee code, Date of Joining, Age, Division, Department and Location.  Each row represents data for one employee.  The number of rows on this worksheet is approximately 700.
  2. Training Data - a multi column dataset with information such as Employee code, Training Date from, Training Date to, Training Program Name, Training Program Category (Internal and External), Training Location and Training Service Provider.  Each row represents one training attended by one employee.  The number of rows on this worksheet is approximately 2,600.

Let’s suppose that the training calendar of this company runs from July to June.  Some questions (only few mentioned for illustration purposes) which a Training Manager may need answers to are:

1)   How may unique employees were trained each year; and
a)   Of the unique employees trained, how many were first time trainees and how many were repeat trainees
i)   Of the first time trainees:
(1)    How many joined this year
(2)    How many joined in past years
ii)  Of the first time trainees:
(1)    How many were trained within the first year of joining
(2)    How many were trained in the second year of joining
(3)    How many were trained in the third year of joining
(4)    How many were trained after three years of joining
iii)  Of the repeat trainees:
(1)    What is the average gap (in days) between trainings
(2)    What is the minimum gap (in days) between trainings
(3)    What is the maximum gap (in days) between trainings

Getting answers to the questions mentioned above would entail writing a lot of lookup related formulas, applying filters, copying and pasting and then creating Pivot Tables.  While the example taken above is that of a training database, you may envision “drilling down to and slicing” any dataset – Marketing, Sales, Purchase etc.

You may watch a short video of my solution here

In these two workbooks, you will be able to see the level to which one can drill down and analyse data using the Power Pivot add-in.  When you open this workbook, please go the first worksheet and make the relevant choice of MS Excel version first so that you start looking at the Analysis from the correct worksheet.

1. Analysing Training data of a company; and
2. Analysing Sales data of a company

You will be able to see the analysis in these workbooks only if you are using one of the following versions of MS Office:

1. Excel 2013 Professional Plus; or
2. Excel 2010 with the Power Pivot add-in installed.  Power Pivot is a free add-in from Microsoft which can be downloaded from here.

Lastly, if you are using the Power Pivot add-in in Excel 2010, you will not be able to see the underlying Data Model or the calculated Field formulas because this workbook has been created in Excel 2013 Professional Plus and unfortunately the Power Pivot model is not backward compatible.  However, all the analysis performed in this workbook can be performed in Excel 2010 as well (with the Power Pivot add-in installed).