Students Struggled With…
Ranking confidence intervals from narrowest to widest depending on degrees of freedom.
Using the correct critical value.
Students will always have a table of t* values. They can look up the t* values for each confidence interval listed and rank the t* values from least to greatest. This will give the same result.
When you are grading quizzes, make sure to look for the critical value and mark partial credit if students use the incorrect one. We found they often used a z* or t* for df = n instead of df = n – 1.