Question

You are contacted by the top cookie-selling Girl Scout troop in the city. As part of their sales plan for next year’s cookie selling season, they need to know (with 90% confidence) if the types of cookies purchased by their customers depends on where the scouts sell them. Here is their confidential sales data from last year:

		Type of Cookie Sold
		Thin Mints	Tagalongs	Do-si-dos	Trefoils	Samoas
Sales Method	At parents’ workplace	472	641	350	223	401
	Door-to-Door	840	1092	673	511	542
	Community Events	683	742	491	420	374

Step 1) What type of hypothesis test is required here?

Step 2) Verify all assumptions required for this test.

Step 3) State the null and alternate hypotheses for this test using correct symbols and notation.

Step 4) Run the correct test in MINITAB and provide the information below. Use correct symbols and round answers to 3 decimal places.

               

Test Statistic
Degrees of freedom

Critical Value
p-value

               

Fill-in the Expected Values of each cell below. Round answers to 2 decimal places.

(Hint: use the output of the statistical test you ran above!)

		Type of Cookie Sold
		Thin Mints	Tagalongs	Do-si-dos	Trefoils	Samoas
Sales Method	At parents’ workplace
	Door-to-Door
	Community Events

Step 5) State your statistical decision and justify it.

Step 6) Interpret your decision within the context of the problem: what is your conclusion?

Answer 1

(1)-> Chi-square test for independent type of hypothesis test is required.

(2)-> The main assumption of this test is each subject contribute to only one cell.

so total subject is 8455 which is equal to sum of all cell frequency which is also 8455.

(3)-> Ho: The types of cookies purchased by their customers doesn't depends on where the scouts sell them.

Ha: The types of cookies purchased by their customers depends on where the scouts sell them.

(4)->

Chi-Square Test for Association: Sales Mathods, Worksheet columns

Rows: Sales Mathods   Columns: Types of Cookie

	Thin Mints	Tagalongs	Do-si-dos	Trefoils	Samoas	All
At Parents workplace	472	641	350	223	401	2087
	492.4	610.9	373.7	284.8	325.1
Door-to-Door	840	1092	673	511	542	3658
	863.1	1070.8	655.0	499.3	569.8
Community Events	683	742	491	420	374	2710
	639.4	793.3	485.3	369.9	422.1
All	1995	2475	1514	1154	1317	8455

Cell Contents
      Count
      Expected count

Chi-Square Test

	Chi-Square	DF	P-Value
Pearson	56.785	8	0.000
Likelihood Ratio	56.622	8	0.000

Test Statistic = 56.785
Degrees of freedom = 8

Critical Value = 13.362
p-value = 0.0000

	Type of Cookie Sold
		Thin Mints	Tagalongs	Do-si-dos	Trefoils	Samoas
Sales Method	At parents’ workplace	492.4	610.9	373.7	284.8	325.1
	Door-to-Door	863.1	1070.8	655.0	499.3	569.8
	Community Events	639.4	793.3	485.3	369.9	422.1

(5) -> Here the p-value is zero, so we have sufficient evidence to reject the null hypothesis.

Therefore Ho is rejected.

(6)-> Hence the types of cookies purchased by their customers depends on where the scouts sell them.