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1.9 Air pollution and birth outcomes, scope of inference: Exercise 1.3 introduces a study where researchers collected data to examine the relationship between air pollutants and preterm births in Southern California. During the study air pollution levels were measured by air quality monitoring stations. Length of gestation data were collected on 143,196 births between the years 1989 and 1993, and air pollution exposure during gestation was calculated for each birth.

a) Identify the population of interest in the study.

the 143,196 birth between the years of 1989 and 1993
the researchers
all birth between the years of 1989 and 1993
the length of gestation data

b) Identify the sample in this study.

the 143,196 birth between the years of 1989 and 1993
the length of gestation data
all birth between the years of 1989 and 1993
the researchers

c) Can the results of the study can be generalized to the population?

Yes, the results can be generalized to the target population.
It depends. If the sample is randomly selected and representative of the entire population, then the results can be generalized to the target population.
No, the results cannot be generalized to the target population.

d) Can the findings of the study be used to establish causal relationships?

Since this study is experimental, the findings cannot be used to infer causal relationships.
Since this study is observational, the results cannot be used to infer causal relationships.
Since this study is observational, the findings can be used to infer causal relationships.
Since this study is experimental, the findings can be used to infer causal relationships.

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