For this week’s discussion, let's consider an example of measuring the effectiveness of a marketing campaign using a random variable. The variable we might choose to measure could be the number of website visits generated by the campaign. The sample space for this variable would be the range of possible website visits, which could be any positive integer value. The probabilities associated with each value in the sample space would depend on the success of the marketing campaign. If the campaign is successful, we might expect higher probabilities for values near the upper end of the sample space, while a less effective campaign might have more uniform probabilities across the range of possible values.
Suppose the goal of the campaign is to generate website visits, and the marketing team has developed a plan to drive traffic to the website through a combination of social media advertising, email marketing, and search engine optimization. The team has set a target of 10,000 website visits over a one-month period for the campaign. However, due to the unpredictable nature of marketing, the actual number of website visits generated by the campaign may vary from this target.
To model this situation using a random variable, we could define the variable X as the number of website visits generated by the campaign over the one-month period. The sample space for X would be the set of all possible positive integer values that X could take on, from 0 to some upper limit. Let's say that we define the upper limit as 20,000 website visits. We can then assign probabilities to each value in the sample space based on our expectations for the success of the campaign. For instance, we might estimate that the probability of generating 10,000 website visits (our target) is 0.3, while the probabilities of generating fewer or more visits could be distributed according to a normal distribution with a mean of 10,000 and a standard deviation of 2,500. Using these probabilities, we can make statistical predictions about the likely range of website visits, and calculate the expected value and variance of the random variable X.
However, it's important to remember that any individual outcome is subject to random variation and unpredictable factors, even if the overall success of the campaign is well-modeled by the random variable X. For example, a major news event or a competitor's marketing campaign could impact consumer behavior in unexpected ways and result in more or fewer website visits than predicted. As a result, while random variables can be useful for modeling marketing effectiveness.
As mentioned above, a random variable is the future outcome of a measurement, before the measurement is taken. If someone claims to know the outcome of an individual observation of website visits generated by the marketing campaign, they are likely overestimating their ability to predict the outcome. While we can use the sample space and associated probabilities to make statistical predictions about the likely range of website visits, any individual outcome will still be subject to random variation. Factors outside of the campaign, such as seasonality, external events, or changes in consumer behavior, could impact the outcome in ways that are difficult to predict.
To summarize, random variables can be useful for modeling situations in which the outcome is uncertain due to random variation, such as marketing effectiveness. While the sample space and associated probabilities can help to provide insights into the range of possible outcomes, it is important to acknowledge that any single outcome is still unpredictable and subject to random variation.
Reference
Yakir, B. (2011). Introduction to statistical thinking (with R, without Calculus). The Hebrew University of Jerusalem, Department of Statistics.