Question

In: Statistics and Probability

In 1912 the luxury liner Titanic on its first voyage across the Atlantic, struck an iceberg...

In 1912 the luxury liner Titanic on its first voyage across the Atlantic, struck an iceberg and sank. Some passengers got off the ship in lifeboats, but many died. Think of the Titanic disaster as an experiment in how the people of that time behaved when faced with death in a situation where only some can escape. The passengers are a sample from the population of their peers. Here is a table showing who survived the sinking of the Titanic based on whether they were crew members, or passengers booked in first-, second-, or third-class staterooms:

crew First Second Third Total
Alive
Dead

212
673

202
123
118
167
178
528
710
1491
Total 885 325 285 706 2201

. Calculate the survival rates (the number who survived divided by the number in the group) for each of the four groups. b. (1 mark) Write null and alternative hypotheses to assess whether group and survival are related. c. Is there strong evidence that the survival rates are not all the same? If not, what differences seem important?

Solutions

Expert Solution

a)

crew first second third
survival rate= 24.0% 62.2% 41.4% 25.2%

b)

Ho: group and survival are related

H1: group and survival are not related

c)

Chi-Square Test of independence
Observed Frequencies
crew first second third Total
alive 212 202 118 178 710
dead 673 123 167 528 1491
Total 885 325 285 706 2201
Expected frequency of a cell = sum of row*sum of column / total sum
Expected Frequencies
crew first second third Total
alive 885*710/2201=285.484 325*710/2201=104.839 285*710/2201=91.935 706*710/2201=227.742 710
dead 885*1491/2201=599.516 325*1491/2201=220.161 285*1491/2201=193.065 706*1491/2201=478.258 1491
Total 885 325 285 706 2201
(fo-fe)^2/fe
alive 18.9148 90.0461 7.390 10.864
dead 9.0071 42.8791 3.519 5.173

Chi-Square Test Statistic,χ² = Σ(fo-fe)^2/fe =   187.7932  
      
Level of Significance =   0.05  
Number of Rows =   2  
Number of Columns =   4  
Degrees of Freedom=(#row - 1)(#column -1) = (2- 1 ) * ( 4- 1 ) =   3  
      
p-Value =   0.0000 [Excel function: =CHISQ.DIST.RT(χ²,df) ]
Decision:    p-value < α , Reject Ho

There is strong evidence that the survival rates are not all the same

in group first class, survival rate is highest


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