Gone are when you could guess your way through marketing campaigns and business decisions. The current data-driven and competitive world requires an analytical approach.
Businesses of all sizes — small, medium, and large — should strive to base their decisions on reliable statistics. But it can be challenging to understand how, when, and which statistical test is appropriate in a given situation.
Decisions based on market research and customer feedback can be the key to more sales and growth, but have you ever wondered what statistical significance is, and how it factors into all this data analysis?
If the phrase “statistical significance” has ever left you feeling lost or confused, then take a deep breath. We will help you through the complex world of statistics as we explore how to determine statistical significance and what it means when something is statistically significant.
Business owners may find themselves stuck in an argument with team members about whether an experiment’s results are significant. Or worse, staring blankly at a complex statistical report and not knowing what it means?
This comprehensive guide will explore statistical significance, explain its importance in data-driven marketing decisions, and discuss the various tests used in data analysis. It will also explain the types of errors and how to use P-values in decision-making.
Read on for the nitty-gritty details about understanding and applying statistical significance measures so that you can make smarter business decisions. It won't take long before you can calculate and interpret statistics like the pro.
What is statistical significance?
Statistical significance measures the probability that the observed results are due to something other than chance. It is a claim that attributes the results to a particular cause.
Statistical significance helps you answer questions like, is the observed mean difference between groups due to chance? Or were these results caused by a specific factor?
It helps you determine if the collected data supports or rejects a hypothesis or claim. To measure statistical significance, researchers use a test statistic. A test statistic is a numerical value that compares the results of a study (sample) against what you would expect if the claim is true.
Here are three reasons why understanding statistical significance is essential for making data-driven decisions in businesses:
It helps identify patterns and correlations
Some relationships are by chance, while others have an underlying cause. A better understanding of this concept allows business owners to separate mere correlations from meaningful relationships and analyze data more accurately.
Facilitates forecasting
With the help of statistical significance, businesses can better understand their data and build reliable forecasts for customer needs or market trends. It helps them plan, make the right decisions, and prepare for potential changes.
It reduces the chance of costly mistakes
Statistical significance is essential for avoiding costly mistakes that arise from an incorrect interpretation, leading to wrong inferences. This can be beneficial in achieving a successful marketing campaign within the budget.
Fundamentals of statistical significance
Hypothesis testing is a cornerstone of statistical analysis and data mining. It is a process used to evaluate a set of assumptions about a population based on collected samples. It is helpful to businesses because it provides insights into future strategies.
The goal of hypothesis testing is to determine if the null hypothesis is true or if the data has statistical significance. The null hypothesis (H0) is an assumption of no change or no effect. The alternative hypothesis (H1) is an assumption of change or effect.
Conducting a statistical test to calculate the probability that an effect exists determines which hypothesis is true. You should accept the alternative hypothesis if the probability of a change or effect is less than a predetermined threshold level (usually 5%).
Hypothesis testing allows better decision-making. Businesses can determine the effectiveness of potential strategies before investing in them. They can evaluate the risks and rewards associated with different actions and make more informed decisions about how best to move forward.
Besides, testing hypotheses measure the validity and reliability of business outcomes. You can identify any flaws in a study and determine the accuracy of its results. It helps you make decisions based on reliable information and confirmed facts.
What is p-value and alpha?
The p-value is a numerical value used to determine the likelihood that the results of an experiment are due to chance. It is also known as the probability value. Its calculation depends on the observed data and expected results from the null hypothesis.
A low p-value (usually less than 0.05) means the observed results are unlikely to be due to chance, and the alternative hypothesis is accepted (considered statistically significant). On the other hand, when the p-value is high (greater than 0.05), you retain the null hypothesis, suggesting that the observed results are likely due to chance.
Alpha (α) is a statistical term used as a threshold for determining whether to reject the null hypothesis. It is a predetermined level of significance used in hypothesis testing and determines the risk of making an incorrect decision.
For instance, if the significance level is 5% (alpha = 0.05), then there is a 5% chance of rejecting the null hypothesis when it is true. In other words, the researcher will accept the alternative hypothesis if there is less than a 5% probability of getting the observed results due to chance.
How to use a p-value to make informed decisions
Business analysts can obtain the p-value from the statistical tables depending on the type of distribution. They can also obtain it using Excel functions and other statistical packages like SPSS and R.
Once you have the p-value, use it to decide whether your data is significant by comparing it with the significance level (alpha). When the p-value is smaller than the predetermined significant value, it suggests the data is significant, and you can accept the alternative hypothesis (H1).
Otherwise, if the p-value is higher than the predetermined significant value, it implies the data is not considered statistically significant, and you retain the null hypothesis (H0). A common saying states that if "P" is low, then H0 must go.
Businesses use a p-value to make data-driven decisions and develop sound marketing campaigns or product launch strategies.
Understanding type I and type II errors
Tests of hypotheses are not perfect. Consider how the legal system operates: sometimes innocent people are wrongfully imprisoned, and the guilty get away with it. Data can also lead to erroneous conclusions.
However, what sets statistical hypothesis tests apart from a legal system is that the framework enables you to quantify and manage the frequency with which the data leads us to the wrong conclusion. Let us explore these erroneous conclusions; type I and type II errors.
Type I
This decision error occurs when you reject the null hypothesis (H0), even though it's true — you falsely reject the null hypothesis. It happens when you make a wrong conclusion that the data is significant, meaning the results did not occur by chance, and there is a cause.
Type I error, also known as a ‘false positive.’ It has an associated level of risk known as the alpha (α) level. The lower the alpha level, the lower your chances of making a type I error. For example, setting an alpha level of 0.05 will reduce the chances of falsely rejecting a null hypothesis to 5%.
Type II
A type II error, also known as a false negative, is a statistical mistake that occurs when an analyst or researcher fails to reject a false null hypothesis. It is when the analyst incorrectly concludes that there is no significant difference between two groups (when in reality, there is a significant difference).
An example of a type II error in business is when a marketing team fails to reject the null hypothesis that their new product will not increase sales, while indeed, it will increase sales. The team might make this error because they lack enough data or evidence to prove that the new product will boost sales. They retained H0, which was false. Bias in statistics provides inaccurate inferences about the population.
Choose the right test statistics
In business analysis, it's essential to choose the right test statistic. Different tests suit different types of data and different situations. Working with a professional statistician is advisable to select the correct statistical test.
There are two main categories of test statistics: parametric and nonparametric tests. Parametric tests are based on assumptions regarding the data, while non-parametric tests do not make assumptions about the data. Some of the commonly used tests are:
Z-test
This parametric test analyzes data when the sample size is small and the population standard deviation (σ) is known. It determines whether two population means are different and measures the relationship between two variables. Business owners use it to compare two means, calculate confidence intervals, and determine differences in proportions.
Z-test can be used to evaluate website analytics and engagements to make data-driven business decisions. It involves comparing website metrics with the average website metrics of the industry or similar websites.
The Z-test will calculate if there are meaningful website traffic differences. The findings can help inform decision-makers about what puts their website above or below other competitors in terms of website engagement.
By zooming into these details, businesses can make well-informed decisions at an optimized cost that promises maximum return on investment.
Chi-square test
A chi-square test is a non-parametric test that compares categorical variables. It determines how well-observed data fits an expected pattern.
It's based on comparing frequencies, or counts, of different categories and is used in various business applications to identify relationships between variables. Business analysts use a chi-square test to analyze quantitative data and make data-driven decisions.
For example, it can be helpful in market research to understand purchasing behavior in various demographic groups. Chi-square tests are also helpful for quality assurance research, enabling businesses to understand customer service trends and whether buyers receive satisfactory products or services. You can use this test to measure email marketing success.
Independent t-test
A two-sample t-test is a statistical analysis used to assess the difference between the means of two independent groups. Both samples should be normally distributed and have a sample size of fewer than 30 observations.
For instance, a company human resource manager may want to determine if hiring part-time workers to replace full-time employees will affect productivity. In this case, the manager will gather data on the productivity of each group to test their claim. The test can also be used in email A/B testing.
Paired t-test
It is also known as a dependent sample t-test because it compares one group against itself at different points in time or under different conditions.
It determines whether there is a statistically significant difference between the two samples by testing whether the mean difference between the two related samples is significant.
The paired t-test is most commonly used to compare the means of two related samples, like before and after training on the same group of individuals or repeated measurements taken from a single group.
It helps determine how much change occurred between the two measurements. It can evaluate the effectiveness of a training program in organizations. The limitation of t-tests is that you can not use them for more than two groups.
ANOVA test
There are two types of analysis of variance (ANOVA) tests: one-way ANOVA and two-way ANOVA. Analysis of variance operates under assumptions of equal variance and normal distribution.
One-way ANOVA compares the means of three or more independent groups. It involves calculating variance between and within groups. It tests whether the means of different groups are equal.
For example, in a study of the effect of three marketing strategies on sales growth, a one-way ANOVA can be used to compare the mean sales growth for each type of strategy.
Two-way analysis of variance (also known as factorial ANOVA) examines the main effects of two factors and their interactions on an outcome variable. It determines if there is an interaction between two independent variables and how they affect a dependent variable.
With two-way ANOVA, the main effects are the main difference between the levels of each independent variable, and interactions are the differences between the main effects.
Two-way ANOVA is used in business to analyze the main effects and interactions of two factors that impact a particular business outcome.
For example, a business may want to assess the main effect of price and promotion on sales. The main effect of price would measure the difference in average sales for different prices, and the main effect of promotion would measure the difference in average sales for different promotional activities.
The interaction between price and promotion would measure the difference in sales when both independent variables (price and promotion) are in play. Two-way ANOVA helps businesses understand how different factors interact and their impact on the company's bottom line.
Choosing the right test statistic is essential for accurate results. The selection of a suitable statistical test depends on the data type, the objectives of your analysis, and the research question you want to answer.
Working with Mailchimp can help you determine which tests are most appropriate for your project and ensure that your results are reliable.
How to interpret results and communicate findings
Interpreting results and communicating findings is the most crucial part of any business analysis. It helps decision-makers understand the data and how they can use it to move the business forward.
When interpreting results, understand the statistical measures used and their limitations. Explain any assumptions made when performing the tests and how they might have affected the results. You should always provide a clear and concise explanation of the findings from the tests, including how statistically significant or insignificant they are.
Use precise communication tools like charts and graphs to help decision-makers understand the data. This way, they can quickly draw meaningful insights from the data. Avoid over-interpretation of results to allow decision-makers to develop insights based on their business operations.
Leverage statistical significance for more data-driven decisions
Statistics play a vital role in business analysis. Understanding p-values and their interpretations are essential for making data-driven decisions.
Choosing the correct test statistic and understanding type I and type II errors will help businesses maintain accuracy in their analysis. It is also essential to understand how to interpret and present findings clearly to help decision-makers draw significant insights from the data.
By following these steps, businesses can make sound decisions that promise maximum return on investment.
Mailchimp provides various tools and services to help businesses make more informed decisions. Mailchimp’s predictive analytics tool can help you predict customer behaviors, such as engagement trends, purchase cycles, and more. With Mailchimp, you can leverage statistical significance to understand your customer base and develop better products and services that meet their needs.
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