PASS 6: Chi Square Test 1. How do Chi Square tests differ from parametric tests? 2. Steps in calculating Chi-Square for goodness of fit: a. Calculate the to remove negative signs b. = O-E c. Divide by d. Add across all to remove the effect of scale(size) Thus the formula for Chi-Square = . 3. How does calculating the Chi-square for goodness of fit differ from Chi-Square for Independence? 4. An ice-cream truck that operates on the North Side of Brisbane wants to try selling their products on the South. They want to see if the North and South have different preferences for their three different flavours: Avocado with Blueberries (AB), Coconut with Dill (CD), and Eggplant with Fish sauce (EF). In the previous month, the sales records of the flavours were recorded (as percentages) in the North side: AB = 50%, CD = 30%, and EF = 20%. The first week of sales in the South were also recorded: AB = 65%, CD = 30%, and EF = 5%. Cell O E O-E (O-E)2 (O-E)2/E AB CD EF x2 = a. What kind of Chi-square test is required to determine if there is a significant difference between North and South sides of Brisbane on flavour preferences? b. Fill out the table above to work out Chi-square c. Explain how the analysis and table would differ if no data was collected from the North side. d. Does South side significantly differ from the North side with regards to their flavor preferences?
5. The same ice-cream truck wanted to know if customers on the North and South had a preference for cups or cones. On the North side, 30% preferred cups and 70% preferred cones. On the South side, it was an even 50%/50% split between cups and cones. Ice-cream Holding Device Cup Cone Side North South Cell A O = E = Cell C O = E = Cell B O = E = Cell D O = E = a. What type of Chi-square test is required to determine if the side of Brisbane influences the type of ice-cream holding device they prefer? b. Fill out the table above and then fill out this table below using the obtained values for O and E. Cell A Calculation, continued O E O-E (O-E)2 (O-E)2/E B C D x2 = c. Is there a preference for cups and cones based on which side of Brisbane a person is from?