Defining the Problem or Question

Before starting any data analysis or building any models, the most fundamental step is to clearly understand and define the problem or question you are trying to address. Just like you wouldn't start building a house without a blueprint, you shouldn't start a data science project without a well-defined objective. Skipping this step often leads to wasted effort, analysis that doesn't answer the right questions, or results that aren't useful to anyone.

A clear problem definition acts as your compass throughout the data science process, guiding your decisions about what data to collect, how to prepare it, what analyses to perform, and how to evaluate your success.

Why is Defining the Problem So Important?

Think about it: if you don't know exactly what you're trying to achieve, how will you know when you've succeeded? A vague goal like "analyze sales data" isn't helpful. What about the sales data? Are you trying to predict future sales? Understand why sales dipped last quarter? Identify the most valuable customers? Each of these implies a different approach and requires different kinds of analysis.

A well-defined problem:

• Provides Direction: It tells you where you're going and helps you stay focused.
• Sets Scope: It helps determine what's included in the project and what's not, preventing the scope from becoming unmanageably large.
• Guides Data Collection: You'll know what kind of data you need to find or gather.
• Informs Analysis Choices: The type of problem dictates the appropriate analytical techniques.
• Defines Success: It makes it possible to measure whether the project achieved its goal.

Characteristics of a Good Problem Definition

How do you move from a general idea to a specific, actionable problem statement? A useful framework is to ensure your problem definition is SMART:

• Specific: The objective should be unambiguous. Instead of "Improve website engagement," try "Increase the average time users spend on blog post pages."
• Measurable: How will you quantify success? Define the metrics. For "Increase average time," the metric is "average session duration on blog pages," and you might aim for a specific percentage increase.
• Achievable: Is the goal realistic given the available data, tools, time, and resources? Aiming to predict the lottery numbers is specific and measurable but not achievable.
• Relevant: Does solving this problem matter? Does it align with broader goals (e.g., business objectives)? Analyzing customer zip codes might be possible, but is it relevant to improving product recommendations?
• Time-bound: When does the problem need to be solved or the goal achieved? This adds practicality. "Increase the average time users spend on blog post pages by 15% within the next quarter."

Not every data science question fits perfectly into the time-bound category, especially exploratory ones, but aiming for specificity, measurability, achievability, and relevance is essential.

Translating Business Needs into Data Questions

Often, the starting point is a business need or a general question from stakeholders (people invested in the project's outcome). A significant part of a data scientist's role, especially early on, is to work with these stakeholders to translate broad goals into specific questions that can be answered with data.

Here's a common scenario:

• Business Need: "We need to reduce the number of customers who stop using our service (customer churn)."
• Initial Data Questions:
  • What is the current churn rate? How has it changed over time?
  • Are there specific groups of customers (demographics, usage patterns) who are more likely to churn?
  • What factors correlate with a customer churning (e.g., number of support tickets, pricing plan, usage frequency)?
  • Can we build a model to predict which customers are at high risk of churning in the near future?

This translation process is iterative and often involves asking clarifying questions.

Translating a general business need into specific, answerable data questions often involves discussion and clarification.

The Role of Context

Defining the problem isn't done in a vacuum. Understanding the context is crucial. What industry are you in? What specific process are you analyzing? What are the known constraints or factors? Domain knowledge, or understanding the specific area you're working in (like finance, healthcare, retail), significantly helps in formulating relevant and insightful questions. Don't hesitate to ask questions to understand the bigger picture.

Getting the problem definition right sets the foundation for the entire data science workflow discussed in this chapter. It ensures that the subsequent steps of data acquisition, preparation, analysis, and communication are all focused on achieving a clear and meaningful goal.