StatisticsdrillChi-square test of independence (2 x 3)
A statistics problem from Statisticsdrill. Solve it with one answer box, with a fresh sample on every attempt and the worked steps and spreadsheet function in the answer, and it is checked the moment you submit.
The task
A survey cross-tabulates preferred contact method by age group. Under 40: email 31, phone 30, chat 86. 40 and over: email 22, phone 35, chat 109. Compute the chi-square statistic for independence, then decide at α = 0.01. Round to 2 decimal places.
What this problem teaches
The formula: E = row total × column total / grand total.
A hint if you get stuck
Expected count = row total × column total / grand total. Then add (O - E)² / E over all six cells. df = (rows - 1)(columns - 1).
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