Psychological Statistics
posted by Anonymous .
A researcher asks participants to sample tap water and bottled water. out of 40 people, 28 selected bottled water. was the bottled water selected significantly more often? Use two tailed test with a+.05

Use the Chisquare (X^2) method with two cells.
X^2 = ∑ (OE)^2/E, where O = observed frequency and E = expected frequency.
∑ = sum of all the cells.
E = (column total * row total)/grand total
df = n  1, where n = number of cells
Look up value in X^2 table in the back of your textbook.