#AP Statistics: Study Design - The Night Before 🌃

Hey! Let's get you prepped for the AP Stats exam. We'll break down study design, which is super important for both multiple-choice and free-response questions. Let's dive in!

#1. Planning Your Study: The Big Picture 🗺️

Before you even think about data, you need a solid plan. This involves:

• Defining your population: Who are you trying to learn about? 🌎
• Choosing your sampling method: How will you select your participants? 😃
• Identifying potential biases: What could mess up your results? ❌

#1.1. Populations vs. Samples

• Population: The entire group you're interested in. Think of it as the whole pie. 🌎
• Sample: A smaller group selected from the population. This is like a slice of the pie. 😃

• Census: Collecting data from everyone in the population. (Very hard to do!) 📄
  • Usually expensive and time-consuming
  • Often conducted by governments

#1.2. Observational Studies vs. Experiments

• Observational Study: You observe and measure, but you don't interfere. It's like watching a nature documentary. ⌛

  • Retrospective: Looking at past data.
  • Prospective: Following individuals into the future.

• Experiment: You impose a treatment and observe the effect. It's like conducting a science experiment. 🧪

  • Key Difference: In experiments, ...