Could I contact the control group?

Separating a control group for data driven marketing test is well known as the best practise. And so should it be, that’s the only way validating your test results and understanding the incremental lift or effect of your marketing activity.

Although still not every company uses control groups in their campaigns, usually with the excuse or reasoning that they can’t leave any customers without the message or added value the marketing activity includes. They consider it as a missed opportunity, since often the control group needs to be as big as 10-25% to gain valid enough test results.

Not contacting your control group, or leaving them without the ‘value add’ feature is the stable of control treatment. But what if you’d challenge the status quo, and contact the control group after the measurement period? When the message is not extremely time sensitive, this could really be an option.

Test results are (or should be) measured within a certain time period, depending on the type of activity and channel. For a simple sales message this is usually something up to 1-2 weeks (often significantly less). There is no reason you couldn’t contact the remaining 10-25%, who were kept as a control group, after the measurement period. Obviously the results can’t be compared to the original results as now the difference is in timing, but this gives you a chance to contact this audience who were left out, and you get some extra sales for ‘free’.

Would you use this tactic in your next campaign?