13. Chi-Square Tests & Goodness of Fit

The table below shows the results from a drug trial for a new ADHD medication. Find the frequencies that we would expect if improvement of symptoms was independent of whether a participant received the placebo.

Suppose a survey records whether $\mathrm{100}$ students prefer coffee or tea ($\mathrm{Coffee:}60$, $\mathrm{Tea:}40$) and whether they are undergraduate or graduate students ($\mathrm{Undergraduate:}70$, $\mathrm{Graduate:}30$). Which two-way table correctly displays this data?

Which of the following cannot be used to display the relationship between two categorical variables?

Which of the following questions can be answered by using a two-way table?