"Computed variables in jamovi" in jamovi Blog does not work?

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by pdeli » Wed Nov 11, 2020 4:32 pm

With Jamovi 1.6.6.0 the "DEMO COMPUTED VARIABLES" video at the top of the page (https://blog.jamovi.org/2017/11/28/jamovi-formulas.html) does not seem to work.

For example:
  1. I clicked on the first field of the first colum;
  2. In the menu selected Data;
  3. Clicked on Add;
  4. Under Computed Variable selected Append;
  5. Double clicked on the header of the first row;
  6. Typed the formula NORM(0,1);
  7. (The check disappeared when compared to version 0.8.0.1 from which the video seems to have been done);
  8. Clicked on the up arrow in a circle.

And nothing happened. Nothing appeared in the column. And it's the same for the rest.

Did I miss something? What did I do wrong?

Thanks for your help.

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I use Jamovi 1.6.6.0 on macOS Catalina (version 10.15.7), MacBook Pro (13-inch, 2019, Four Thunderbolt 3 ports), 2.8 GHz Quad-Core Intel Core i7, 16 GB 2133 MHz LPDDR3, Intel Iris Plus Graphics 655 1536 MB.
pdeli
 
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by MAgojam » Wed Nov 11, 2020 8:40 pm

pdeli wrote:And nothing happened. Nothing appeared in the column. And it's the same for the rest.

Did I miss something? What did I do wrong?


Hi, @pdeli.

What happened is due to the fact that you tried to compute a new variable without there being any cases (rows) in your jamovi sheet.
If I had at least one variable, even with a few cases, everything would have worked.

Let's try this:
Open the jamovi 1.6.6 of your PC or that of the Cloud and you will find yourself with three columns/variables (A, B, C) empty in the sheet.
Try entering 1 in the first row of column A and 30 in row thirty, of column A.
Jamovi now knows you have 30 cases (even if you only entered two values).
Now calculate your variable to have a standardized normal distribution using NORM (0, 1) as you did before without success.
You will find your variable with 30 values to use ...

Cheers,
Maurizio
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by pdeli » Thu Nov 12, 2020 12:02 pm

Hello @MAgojam,

Thanks for your answer which worked indeed. I don't understand how and why, though (even after having erased any data in the first column generated data remained), but that's ok.

A question though: can we say shown results are simulations?
pdeli
 
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by MAgojam » Thu Nov 12, 2020 6:04 pm

pdeli wrote: I don't understand how and why, though (even after having erased any data in the first column generated data remained)


Hi, @pdeli.

What you see is the dynamic behavior of a function like NORM (and others) when it calculates a new variable, which needs the presence of cases in the sheet to generate the vector (variable) with the values ​​of interest.
Once the computed variable is available in the sheet, it will not be affected by deleting other variables (in our case A), but will always be sensitive to adding or deleting cases (rows).
Now, looking at what happens to the computed variable, try entering a numeric value in column A (for example in row 35) and you will see that the computed variable has regenerated with new values ​​and extending to row 35 to ensure a standardized normal distribution for a sample of 35 cases.
Now, try to delete some cases (rows), for example rows 5 to 9 inclusive and you will see that the computed variable will regenerate again with new values, to give you a distribution with a sample of 30 cases.
Have fun experimenting ...

Cheers,
Maurizio
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by pdeli » Fri Nov 13, 2020 10:30 am

Absolutely brilliant! :grinning:

Thank you very much for your explanation @MAgojam.
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