Inference, Confidence, and Hypothesis Testing
Using samples to make conclusions
What is statistical inference?
Statistical inference uses sample data to make conclusions about a population while acknowledging uncertainty.
Confidence and uncertainty
A confidence interval gives a range of plausible values for a population quantity. The idea is to estimate a population parameter from a sample statistic.
Important terms
Beginner rule
Inference is about being reasonable with uncertainty, not about proving something with absolute certainty.
What is a statistic?
A statistic comes from sample data.
Correct answer: A number calculated from a sample
What does a confidence interval do?
Confidence intervals express uncertainty in an estimate.
Correct answer: It gives a plausible range for a population value.
Which statement best describes the null hypothesis?
The null hypothesis usually states that nothing special is happening.
Correct answer: It is a starting claim of no difference or no effect
Why does inference involve uncertainty?
Sampling variation means conclusions are never completely certain.
Correct answer: Because a sample may not perfectly represent the whole population.