Problem 10:

Read the studies described below and answer the following questions.

(Study 1) Researchers collected data to examine the relationship between pollutants

and preterm births in Southern California. During the study air pollution levels were

measured by air quality monitoring stations. Specifically, levels of carbon monoxide

were recorded in parts per million, nitrogen dioxide and ozone in parts per hundred

million, and coarse particulate matter (PM10) in

g/m3. 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. The analysis suggested that

increased ambient PM10 and, to a lesser degree, CO concentrations may be associated

with the occurrence of preterm births.

(Study 2) The Buteyko method is a shallow breathing technique developed by Kon-

stantin Buteyko, a Russian doctor, in 1952. Anecdotal evidence suggests that the

Buteyko method can reduce asthma symptoms and improve quality of life. In a sci-

entific study to determine the effectiveness of this method, researchers recruited 600

1

STAT 3011, Fall 2021

asthma patients aged 18-69 who relied on medication for asthma treatment. These

patients were split into two research groups: one practiced the Buteyko method and

the other did not. Patients were scored on quality of life, activity, asthma symptoms,

and medication reduction on a scale from 0 to 10. On average, the participants in

the Buteyko group experienced a significant reduction in asthma symptoms and an

improvement in quality of life.

a) What is the type of each study?

b) What is the sample of each study?

c) What is the type of sample? Select from

{

random sample, convenient sample,

volunteer sample, or unknown

}

d) What are the explanatory variable and response variable of each study?

e) Based on the descriptions given, can we establish causal relationships between the

explanatory variable and response variable in each study?