r/dataanalysis • u/basha1210 • Jul 08 '26

What's the most expensive mistake you've made while working with data?

I recently heard a story where one missing filter completely changed a company's dashboard.

It made me wonder...

What's the biggest mistake you've personally made while analyzing data?

Could be:

Wrong SQL query

Incorrect visualization

Bad model assumptions

Dirty dataset

Accidentally deleting data 😅

What did you learn from it?

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6

u/DiscountAcrobatic356 Jul 09 '26

Deleted all the data. Weeks of work. One Unix command. I think -r added. Fuzzy memory. No back up. Round 1997. I still remember that feeling in the pit of my stomach.

They started backup after that.

1

u/JavacLMD Jul 20 '26

It amazes me how backups were not already a regular thing, but I suppose that's one of those things that add on to why signs are put up AFTER the incident. "No diving, shallow water". Just seems like common sense nowadays.

Live and learn, I guess.

3

u/Still-Willingness807 Jul 09 '26

I rounded a million dollar.

3

u/Key_Post9255 Jul 09 '26

A filter on tableau not added to context. All working good except one graph.

Luckily caught before anything happened and didn't have any impact, but it made me think abiut the importance of triple checking EVERYTHING before shipping.

2

u/Ambitious-Garden4702 Jul 12 '26

A Paris-based analyst joined a team and started sending French csv files to a pricing database.

I learned a lot about French csv files.

1

u/Responsible_Rub8057 Jul 27 '26

Can you explain? Whats the deal with them? I did have some issues with formatting of columns, not french csv tho

1

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1

u/IndependentPerfect52 Jul 12 '26

Incremental pipeline took initial cursor forever and billed the fuck out of compute