Have you ever delivered an analysis, only to hear from your client that “these numbers can’t be right”? It’s hard to convince someone that your results are credible when they don’t even pass the first 5 seconds of review. As much as we may not want to admit it, sometimes the numbers are indeed wrong, so how do we avoid these situations from happening? One type of check that a Data Team can adopt is the “Consistency Check”. Here are some questions that you can ask yourself when doing a consistency check:
Question 1) Are the numbers consistent with themselves?
When building complicated analyses, different sections of the analysis can fall “out of sync” with each other if they are not all updated in the same way. When this happens it can produce inconsistent summary results (i.e. the cover page reports 255 conversions per hour, but the supporting details on other pages show 237 conversions per hour). Sometimes we place too much faith on our reporting tools and assume that they will report exactly as intended. In other situations it’s just a matter of being too close to the work. After a while the numbers are burned into your short term memory and you lose your ability to critically review them with an objective eye. Suggested work-arounds include:
- Have another member of your team do a consistency check on the results, preferably someone who hasn’t been involved in the work.
- Take an old school approach. Print out the results, and use different colored highlighters for each type of metric. Highlight the summary numbers that represent the same result, and confirm that they are indeed consistent. Continue until you’ve highlighted all summary numbers.
- Take another old school approach. Get your calculator out or use a separate spreadsheet, and confirm that you can replicate the summary numbers just based on the results that are being presented. You may be surprised with how many of your clients are doing this with your results already.
Question 2) Are the numbers consistent with your previous analyses?
When a client receives a new set of results they often pull up the previous results that you gave them. They are asking the question “how much have things changed?” You can beat them to the punch by doing this consistency check yourself. To be more specific:
- Start with the previous result that was presented or released. Compare the summary numbers from the previous results to your current summary numbers.
- Assess if the changes are interpretable. If they are, then this interpretation will likely be part of what you communicate when you release the new results. If the changes are not interpretable, then it’s time to go back into your current results, or your previous results to diagnose why the changes aren’t explainable.
Question 3) Are the numbers consistent with other reports?
Stepping into the shoes of your audience, you can think about the other reports that they are referring to on an on-going basis. It doesn’t matter if the other reports that they use came from a completely different source – from their perspective all data from all sources is supposed to tell the same story. In a similar manner to Question 2, you can do some additional homework so that your results are valuable to your audience as possible. For example you could:
- Ask your clients if they have any other reports that they use frequently, and if they would be willing to share them with you. You can frame it honestly – you want to make sure that your results are valid, and if they are different from other sources, you want to be able to explain why.
- Do a little research on your own, in particular, reviewing any routine corporate reporting, or industry reporting. Sometimes, a skeptic can be won over by proving that you did your homework. Again if the numbers line up from other sources, it becomes something you can report as proof of consistency. If the numbers don’t line up and you can’t explain the difference, then it may be an indication that you need to review your analysis.
Question 4) Are you telling the right story?
Taking all of the above into account, you should be able to deliver your results confidently. You should now know that the numbers in the report are consistent amongst themselves, that the analysis is consistent with previous analyses, and that the results are interpretable in comparison to other sources. This now can become part of your summary and presentation of your stunning new work. Or at least it can form as an addendum to the email, or the presentation that shows your audience the efforts that you went through to ensure that the numbers are the right numbers. Then you have the foundation to begin telling the actual story of the analysis (the “so what” message).
These are just a few tips, but I’m sure there are many of experts out there who have many more great ideas. If you have suggestions, or alternate points of view, please weigh in.
Note: What is a Data Team?
When we refer to “Data Teams” it’s a catch all for groups of technical, statistical, and subject-matter domain experts that are involved in providing information to support their organization. These teams are sometimes called “Business Intelligence”, “Decision Support”, or “Information Management”, but they can also be internal consultants such as “Operations Analysts”, “Strategic Information” or “Research”. Many of these concepts equally apply to teams of Data Scientists.