Importance of Sample Size

Submitted by mmm on Wed, 10/14/2015 - 16:20

It is important for law firms and disability practices to pursue different types of marketing in order to identify which is the best fit for their business. There are many attorney marketing options available. With that said, they are all very different. Therefore, it is important to give each marketing campaign enough time for attorneys and advocates to receive a large enough sample of leads, whether it be through lead generation companies or inbound marketing, before making any judgments as to whether or not that particular campaign is the best fit for that firm.

Having a large sample size to evaluate will give an accurate representation as to the quality of the population generated from a particular marketing source. As there are many things that can affect the quality of a particular sample population, as you read on you will find our recommendation in order to ensure your firm is giving its marketing campaigns enough time before prematurely making any judgments.

Determining sufficient sample size

Different types of marketing sources require different types of benchmarks, as there are many factors that play into having a sufficient, valid, and reliable sample to make judgment from. Regardless of the attorney marketing options available, there will always be room for error in terms of the sample size a firm ultimately decides to test.

It is a statistical industry practice to utilize a sample population large enough that it gives a confidence interval of 95%. In other words, sampling a large enough sample so that it is statistically accurate 95% of the time. If this is not taken into consideration, results may be skewed due to small sample or end up oversampling, which would hurt company profitability if the marketing efforts were not successful.

How you calculate what sample size is needed in order to be 95% confident in the results? There are some market research professionals who use the following formula1 to establish the true a sufficient sample to test. This way, when doing their market research, they do not over-sample/ under-sample and company time and money.

N=(Z21-a/e2)*(1-p)

Simplified Sufficient Sample Size

Realistically, law firms and advocacy groups are not going to be using the N formula listed above to calculate the sufficient sample. Industry leaders, such as Dr. Saiful whom is a clinical researcher, states that “sample size larger than 30 and less than 500 are appropriate for most research”.2 Although his findings are for market research, the same can be applied to evaluating lead generation campaigns and other types of marketing sources.

For clients who utilize our service, we require no minimum. However, we do recommend our clients to accrue a sample of at least 100 legal leads before making any decision as to whether or not lead generation was the right marketing avenue for their law firm or advocacy group.

Our Marketing Campaigns

Our recommendation to clients is actually something we put into practice every day as we generate our leads from a variety of marketing sources. If our clients update the lead result within their eLuminate account, we are able to identify which campaigns are producing the leads that convert into cases, and thus accumulate an adequate sample of leads we can evaluate before adjusting campaigns in order to optimize campaigns and increase lead quality.

If you have any questions regarding our service, feel free to contact us today!

1 Groebner, David F., Patrick W. Shannon, and Phillip C. Fry. Business Statistics A Decision-Marking Approach. 3rd ed. Boston: Pearson, 2014. Print.
2 “Sample Size.” Accessed on 20 June 2011.