How to select a random sample from all your data [trick]

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The other day, I got a text message (SMS) from one of our readers. It read,

How to select random samples from data in Excel?

So today, let us learn a very easy trick to select random sample from your data.

Lets take a look at the data

Since the text message has no actual data, I made up this.

Random samples needed from this data set

Now, if you just want to select any 10 (or x number of) random items from this list, then your job would very simple.

  1. Shuffle (or randomly arrange) this list
  2. Just pick first 10 items

But our problem is to get 2 random samples per user.

Selecting random samples from data

Follow below steps.

  1. Add an extra column and fill it with =RAND() formula. This generates random fraction between 0 and 1.

    Add RAND() function to the adjacent column

  2. Create a pivot table from this data (tutorial: How to create a pivot table?)
  3. Add User ID & Case ID as Row labels and Random as value field.
    Pivot table layout for selecting random samples
  4. Click on the filter icon on Case ID column, choose Value filter > Top 10
  5. Filter for top 2 random values. (related: Filter top 10 values in pivot tables – how to?)

    Pivot Table value filters - filtering top 2 values

  6. Adjust report layout (Table layout, no sub-totals, no grand totals)

    Report layout to show just the samples and nothing else

  7. Done!

Final random samples - easy and awesome.

To see new samples

Just select any cell in the pivot table, press ALT+F5. Your pivot table will be refreshed and you get new samples.

That is just easy and awesome!

Download Example Workbook

Click here to download the example file. Refresh the pivot table (ALT+F5) to see fresh samples.

Do you sample your data?

Drawing samples, running experiments, analyzing results are life breath for many businesses. As business data is growing, these analytical skills  are becoming important.

How do you draw samples? What techniques you use when analyzing the data? Please share your stories, experiences & tips using comments.

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13 Responses to “Data Validation using an Unsorted column with Duplicate Entries as a Source List”

  1. Vipul says:

    Pivot Table will involve manual intervention; hence I prefer to use the 'countif remove duplicate trick' along with 'text sorting formula trick; then using the offset with len to name the final range for validation.

  2. Rich says:

    if using the pivot table, set the sort to Ascending, so the list in the validation cell comes back alphabetically.

  3. Kieranz says:

    Hui: Brillant neat idea.
    Vipul: I am intrigued by what you are saying. Please is it possible to show us how it can be done, because as u said Hui's method requires user intervention.
    Thks to PHD and all
    K

  4. sam says:

    Table names dont work directly inside Data validation.
    You will have to define a name and point it to the table name and then use the name inside validation
    Eg MyClient : Refers to :=Table1[Client]
    And then in the list validation say = MyClient

  5. Vipul says:

    Kieranz,
    Pls download the sample here http://cid-e98339d969073094.skydrive.live.com/self.aspx/.Public/data-validation-unsorted-list-example.xls
    Off course there are many other ways of doing the same and integrating the formulae in multiple columns into one.

  6. Vipul says:

    Pls refer to column FGHI in that file. Cell G4 is where my validation is.

  7. Kieranz says:

    Vipul:
    Many thks, will study it latter.
    Rgds
    K

  8. [...] to chandoo for the idea of getting unique list using Pivot tables.  What we do is that create a pivot table [...]

  9. Playercharlie says:

    @Vipul:

    Thanks, that was awesome! 🙂

  10. Vipul says:

    @Playercharlie Happy to hear that 🙂

  11. Enrique says:

    Great contribution, Hui. Solved a problem of many years!

  12. FARIS says:

    Thanks to you, A LOT

  13. Mohamed says:

    Hi Hui,
    Greeting
    hope you are doing well.
    I'm interested to send you a private vba excel file which i need to show detail of pivot in new workbook instead of showing in same workbook as new sheet.

    Please contact me on muhammed.ye@gmail.com

    Best Regards

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