[17.9] the chi-squared test

Question 1

what is the chi-squared test used to test?

Answer 1

whether any deviation between the observed and expected numbers in an investigation is significant or not

Question 2

what criteria are necessary to use a chi-squared test?

Answer 2

• relatively large sample size >20
• discrete data
• only raw scores, not percentages etc.
• used to compare experimental results with theoretical ones

Question 3

what is the formula for chi²?

Answer 3

X² = Σ (observed value - expected value)² / (expected value)

Question 4

how do you find the degrees of freedom?

Answer 4

number of categories - 1

Question 5

when should you accept the null hypothesis based on the critical value table?

Answer 5

• calculated value is smaller than critical value
• there is more than 5% probability that the differences between observed and expected values is due to chance
• we accept the null hypothesis

Question 6

when should you reject the null hypothesis based on the critical value table?

Answer 6

• calculated value is greater than critical value
• there is less than 5% probability that the differences between observed and expected values is due to chance
• we reject the null hypothesis