What's the best way to determine the right sample size and duration for lead generation testing?

1 Why sample size and duration matter

The sample size and duration of your lead generation tests affect the validity and reliability of your results. A valid test means that you measure what you intend to measure, and a reliable test means that you get consistent results over time. If your sample size is too small or your duration is too short, you may not have enough data to draw meaningful conclusions or detect significant differences between your variations. On the other hand, if your sample size is too large or your duration is too long, you may waste time and money on unnecessary testing or miss out on opportunities to improve your performance.

2 How to calculate sample size

The sample size of your lead generation test is the number of leads you need to collect from each variation to reach a certain level of statistical significance and power. Statistical significance means that the difference between your variations is not due to chance, and power means that you have enough data to detect a meaningful difference. To calculate your sample size, you need to know four factors: the baseline conversion rate, the minimum detectable effect, the significance level, and the power level. You can use online calculators or formulas to estimate your sample size based on these factors, or you can use tools like Google Optimize or Optimizely that do it for you.

3 How to determine duration

The duration of your lead generation test is the time period you need to run your test to collect enough data for your sample size. The duration depends on your traffic volume, your conversion rate, and your test design. Generally, you want to run your test for at least a full week to account for any seasonal or weekly variations in your traffic and conversions. You also want to avoid running your test for too long, as external factors like competitors, trends, or events may affect your results. You can use online calculators or formulas to estimate your duration based on your traffic and conversion rate, or you can use tools like Google Optimize or Optimizely that monitor your test progress and notify you when it's done.

4 How to adjust sample size and duration

Sometimes, you may need to adjust your sample size and duration based on your practical constraints or changing circumstances. For example, if you have a limited budget or a tight deadline, you may want to reduce your sample size and duration by accepting a lower level of significance or power, or by increasing the minimum detectable effect. Alternatively, if you have a high budget or a flexible timeline, you may want to increase your sample size and duration by aiming for a higher level of significance or power, or by decreasing the minimum detectable effect. However, you should always make these adjustments before you start your test, and never change them midway, as that would compromise the validity and reliability of your results.

5 How to avoid common pitfalls

There are some common pitfalls that you should avoid when determining the sample size and duration for your lead generation tests. One of them is stopping your test too early or too late, based on your gut feeling or arbitrary thresholds. You should always follow the sample size and duration that you calculated beforehand, and wait until your test reaches statistical significance and power before you declare a winner or a loser. Another pitfall is testing too many variations or factors at once, which would increase your sample size and duration exponentially and make it harder to isolate the effects of each variation or factor. You should limit the number of variations or factors you test at a time, and prioritize the ones that have the most potential impact on your conversions.

6 How to apply your results

Once you have determined the right sample size and duration for your lead generation test, and run your test accordingly, you can analyze and apply your results to improve your marketing campaigns and generate more qualified leads. You can compare the performance of your variations or factors based on metrics like conversion rate, cost per lead, lead quality, and return on investment. You can also use tools like Google Analytics or HubSpot to track the behavior and outcomes of your leads throughout the funnel. Based on your results, you can implement the winning variation or factor, or run further tests to optimize your lead generation strategy.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?