Question

Statistical Significance for 2 x 2 Tables Graded Assignment | Read Chapter 13| Back to Assignment Due Friday 04.26.19 at 11:00 PM Keep the Highest: 0.2/1 Attempts: 0.2 2. Chi-square tests for tables larger than 2 x 2 Aa Aa The Chernobyl accident in Ukraine in 1986 is considered the worst nuclear plant disaster in history. Suppose you are a researcher conducting a study to determine whether the Chernobyl accident caused an increase in thyroid cancer among children in southern Belarus. You collect a random sample of 123 children with thyroid cancer and a random sample of 123 children without thyroid cancer from this region. The thyroid dose from radioactive iodine (131I) is estimated for each child and categorized into three intervals-less than 0.30 Gy, from 0.30 to 0.99 Gy, and 1.00 Gy or more Select and read the appropriate background notes: The following contingency table compares the samples of children with and without thyroid cancer in terms of their counts in the three thyroid-dose intervals Estimated Thyroid Dose from 1311 Total 123 123 246 <0.30 Gy 61 78 139 0.30-0.99 Gy 32 26 58 1.00+ Gy 30 19 49 With thyroid cancer Without thyroid cancer Total In the sample of children with thyroid cancer, the proportion of children with an estimated thyroid dose in the <0.30 Gy interval IS <0.30 Gy interval is . In the sample of children without thyroid cancer, the proportion of children with an estimated thyroid dose in the (Round your proportions to two decimal places.) You would like to determine whether the proportions across the three dose intervals is different for those children with thyroid cancer than those without. You plan to conduct a chi-square test. The null and alternative hypotheses are: O Null hypothesis: A lower proportion of children with thyroid cancer had a dose of <0.30 Gy than among those without thyroid cancer Alternative hypothesis: The same proportion of children with thyroid cancer had a dose of <0.30 Gy than among those without thyroid cancer O Null hypothesis: The proportions across the three dose intervals are the same for both populations Alternative hypothesis: The proportions across the three dose intervals are different across the two populations ONull hypothesis: The same proportion of children with thyroid cancer had a dose of <0.30 Gy than among those without thyroid cancer Alternative hypothesis: A lower proportion of children with thyroid cancer had a dose of <0.30 Gy than among those without thyroid cancer Null hypothesis: The proportions across the three dose intervals are different across the two populations Alternative hypothesis: The proportions across the three dose intervals are the same for both populations

Answer 1

a).in the sample of thyroid cancer the proportion of children with an estimated thyroid dose in the <0.30 gy interval is:- (61/123)

in the sample of without thyroid cancer the proportion of children with an estimated thyroid dose in the <0.30 gy interval is:-   (78/123)

b).null hypothesis:the proportion across the three dose intervals are same for both the population.

alternative hypothesis:the proportion across the three dose intervals are different across the two population.

c).the expected cell count of children with an estimated thyroid dose in the <0.30 gy in the sample with thyroid cancer is:- 69.50

d).the contribution of the first row and first column is:- 1.040

e).the value of test statistic:- 5.169 ~ 5.2

f).because the value of degree of freedom for the chi-square test is:- 2

g).accept the null hypothesis.

you can not conclude that the proportion across the three dose intervals are different.