Question

In: Statistics and Probability

Wally Watchmaker is interested in determining the preferences for digital vs analog watches. He samples 200...

  1. Wally Watchmaker is interested in determining the preferences for digital vs analog watches. He samples 200 individuals and asks them their age and their preference. Test at an α = .05 to determine if age and watch preferences are independent of each other

  

Age

Digital

Analog

Undecided

Younger than 30

90

40

10

Older than 30

10

40

10

Solutions

Expert Solution

Wally Watchmaker is interested in determining the preferences for digital vs analog watches. He samples 200 individuals and asks them their age and their preference. We are to test at an α = .05 to determine if age and watch preferences are independent of each other.

For this we apply chi-square test of independence between the variables.

We are to test,

H0: Age & watch preferences are independent of each other vs. H1: Age & watch preferences are dependent

The test-statistic is:

The observed frequencies are tabulated as:

OBSERVED

Age

Digital

Analog

Undecided

Marginal

Younger than 30

90

40

10

140

Older than 30

10

40

10

60
Marginal 100 80 20 200

The expected frequencies are tabulated as:

OBSERVED

Age

Digital

Analog

Undecided

Younger than 30

70

56

14

Older than 30

30

24

6

Where, Expected frequency of a cell= (Row total * Column total)/Total frequency

degrees of freedom for the test statistic= (No. of rows)*(No. of columns)-1= (3-1)*(2-1)= 2

Given, level of significance= = 0.05

Clearly, 39.0959(observed)>5.991(tabulated or expected,as obtained from Values of chi-square table)

So, according to the sample we can conclude that, age & watch preferences are strongly related/dependent to each other.


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