benefits vary by the size of the company (the Henry J. Kaiser Family Foundation website, June 23, 2016). The sample data below show the number of companies providing health insurance for small, medium, and large companies. For the purposes of this study, small companies are companies that have fewer than  employees. Medium-sized companies have  to  employees, and large companies have  or more employees. The questionnaire sent to  employees asked whether or not the employee had health insurance and then asked the enployee to indicate the size of the company.     Health Insurance   Size of Company Yes No Total     Small 31 19

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Health insurance benefits vary by the size of the company (the Henry J. Kaiser Family Foundation website, June 23, 2016). The sample data below show the number of companies providing health insurance for small, medium, and large companies. For the purposes of this study, small companies are companies that have fewer than  employees. Medium-sized companies have  to  employees, and large companies have  or more employees. The questionnaire sent to  employees asked whether or not the employee had health insurance and then asked the enployee to indicate the size of the company.

 

  Health Insurance
  Size of Company Yes No Total  
  Small 31 19 50  
  Medium 70 5 75  
  Large 88 12 100  

 

a. Conduct a test of independence to determine whether health insurance coverage is independent of the size of the company. What is the -value?

Compute the value of the  x^2 test statistic (to 2 decimals).

b. A newspaper article indicated employees of small companies are more likely to lack health insurance coverage. Calculate the percentages of employees without health insurance based on company size (to the nearest whole number).

 

Small   
Medium   
Large   
Expert Solution
Step 1

NOTE: As the significance level, i.e, α is not mentioned, I am taking it as 5%, i.e, 0.05.

a).

The null hypothesis (H0) states that health insurance coverage is independent of the size of the company.
The alternative hypothesis (Ha) states that health insurance coverage is dependent of the size of the company.

First we will depict the information in a proper manner.  The given frequencies are the observed frequencies. It is shown as:

Observed Frequencies (O)
  Yes No Row Total
Small 31 19 31+19=50
Medium 70 5 70+5=75
Large 88 12 88+12=100
Column Total 31+70+88=189 19+5+12=36 (189+36) or (50+75+100)=225

Now, we have to calculate the expected frequencies. The formula for expected frequencies is:

Expected frequency=Row total*Column totalGrand total

The following table shows the calculations of the expected freqncuies:

Expected Frequencies (E)
  Yes No
Small 50*189/225=42 50*36/225=8
Medium 75* 189/225=63 75*36/225=12
Large 100*189/225=84 100*36/225=16

The following table shows the required calculations for the  χ2 test statistic.

O E (O-E)2 (O-E)2/E
31 42 121 2.881
19 8 121 15.125
70 63 49 0.7778
5 12 49 4.0833
88 84 16 0.1905
12 16 16 1

The formula and calculations for the χ2 test statistic is as follows;

 χ2=(O-E)2E    =2.881+15.125+0.7778+4.0833+0.1905+1    =24.0576    24.06

Thus, the χ2 test statistic=24.06

The degree of freedom for the χ2 test is calculated as:

Df=(Number of rows-1)*(Number of column-1)
    =(3-1)*(2-1)
    =2

Now, observe χ2=24.06 and df=2 in the χ2 table to obtain the p-value.
The p-value obtained is less than 0.00001

The decision rule states that if the p-value is less than the significance level, we Reject the null hypothesis.

In this case, 0.00001<0.05, Hence We Reject the null hypothesis.
Therefore, It is concluded that health insurance coverage is dependent of the size of the company.

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