Chi-squared test

High school (ages 12+)
Mathematics & Numbers

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/chi-squared-test

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the developed by?Karl Pearson
2. What is the year introduced?1900
3. Why do scientists use a chi-squared test?Scientists use it because it can look at categories like colors, types of animals, or answers to questions, and tell them if the pattern is surprising or normal. It works even when the data are not numbers that can be averaged.
4. How does a chi-squared test decide if something is true or not?First, the test guesses what the numbers should be if nothing special is happening (the null hypothesis). Then it compares the real numbers to those guesses using the formula χ² = Σ[(O–E)²/E]. If the result is bigger than a special cut‑off number, the guess is probably wrong.

Non-parametric Test: A statistical test that does not assume the data follows a specific probability distribution.
Null Hypothesis (H₀): A statement of no effect or no difference, which the test aims to disprove.
Degrees of Freedom: A parameter that determines the shape of the chi-squared distribution, related to the number of categories.
Significance Level (Alpha): The probability of rejecting the null hypothesis when it is actually true (Type I error rate).