A study was undertaken to determine the strength of association between several risk factors and the duration of pregnancies. The risk factors considered were mother\'s age, nutritional status, history of tobacco use, and history of alcohol use. The response of interest, pregnancy duration is a three-categories variable that was coded as follows:

Yi	Pregnancy Duration Category
1	Preterm
2	Intermediate term
3	Full term

We would like to study the association between the duration of pregnancy and risk factors.

(a) Propose an appropriate model and explain how you assess whether your model is adequate

(b) Describe how to estimate the parameters in your model in a step by step manner

(c) We would like to test which risk factors are associated to the pregnancy duration. Explain what test statistic is used and why this test statistic is appropriate. Provide testing procedure in a step by step manner.

(d) We also would like to calculate the prediction accuracy of your model in (a). How would you measure the prediction accuracy of your model? Explain your procedure in a step by step manner.