Question

Suppose a marketing research firm would like to examine if the social networking site that a person primarily uses is influenced by his or her age. In a randomly drawn​ sample, 344 social network users were asked which site they primarily visited. These data are presented in the following table along with each​ person's age group.

Age Group	Site A	Site B	Site C
2-17	26	14	2
18-34	90	35	12
35-54	92	19	18
55+	27	3	6

A. Using a significance level of 0.01, perform a​ chi-square test to determine if age group and social networking site used are independent of one another.

***Calculate the​ chi-square test statistic. If​ necessary, combine age groups.

X2=

(round to two decimal place)

*** Find the​ chi-square critical​ value, (X to the power of 2, significance level, it wouldn’t let me post the symbol so I described it)

X to the power of 2, significance level=

(round to two decimal places)

B. Determine the​ p-value using technology and interpret its meaning.

p-value =

(round to three decimal places)

Answer 1

A)Adding group 35-54 and 55+ to make expected frequency of at least 5 in each cell"

Applying chi square test of independence:

Observed		Site A	Site B	Site C	Total
	2-17	26	14	2	42
	18-34	90	35	12	137
	35+	119	22	24	165
	total	235	71	38	344
Expected	Ei=row total*column total/grand total	Site A	Site B	Site C	Total
	2-17	28.692	8.669	4.640	42
	18-34	93.590	28.276	15.134	137
	35+	112.718	34.055	18.227	165
	total	235	71	38	344
chi square    χ2	=(Oi-Ei)2/Ei	Site A	Site B	Site C	Total
	2-17	0.253	3.279	1.502	5.0332
	18-34	0.138	1.5989	0.6489	2.3855
	35+	0.350	4.2674	1.8287	6.4462
	total	0.7404	9.1452	3.9792	13.865
test statistic X2 =		13.86

B)

degree of freedom(df) =(rows-1)*(columns-1)=

4

p value from excel =

chidist(13.86,4) =

0.008