Determine the study type and reason for it. Relevant measure of frequency OR association?

A. Researchers were interested in whether access to parks and green space predicts depression in children. Using Medicare data, they were able to calculate average levels of depression in children under 16 for administrative areas in Australian cities for 2020. Using planning data, they calculated levels of green space for each administrative area for the same year. Higher levels of green space predicted lower levels of depression in children. The researchers cautioned against overinterpreting the results.

B. A total of 3,324 plumbers was identified via registration data from the Victorian Building Authority. Each was sent a survey on their experience of back pain over the preceding month. 14% of the respondents reported having experienced at least one episode of back pain.

C. There is an effective vaccine to prevent pertussis (whooping cough) infection in infants. However, it cannot be given until 2 months of age and the majority of severe pertussis cases and deaths occur in infants younger than 2 months. Researchers conducted a study to see if maternal vaccination could provide indirect protection against pertussis infection in infants before they can be vaccinated. A group of 118 infants without a history of pertussis infection were recruited alongside 118 infants with a known history of pertussis infection. Data was collected on maternal pertussis vaccination. Maternal vaccination was found to be protective against pertussis infection in infants.

D. Researchers were interested in the occurrence of hearing impairment in professional musicians. A sample of 1,423 professional musicians aged 30+ years without a history of hearing impairment were followed from 2001 to 2020. Diagnoses of hearing impairment were made at yearly intervals. The study found 270 new cases of hearing impairment by the end of the study.

E. A total of 2,423 farm workers employed between 1971 and 1986 were identified from the tax records in 2015. Approximately one-third of the workers were exposed to organophosphate insecticides due to their type of farm work, while the remaining workers were not exposed. Investigators attempted to identify and contact all of these workers, or to access their medical records if they were deceased. The researchers had postulated that exposure to organophosphates increases the risk of Parkinson's disease.

F. A study set out to investigate if the consumption of artificial sweeteners is a cause of anxiety in children and adolescents. Investigators randomly selected a sample of 2,347 students, 7-18 years of age. The students were provided with a survey that asked about beverage consumption and also included a standardised measure for symptoms of anxiety. The results suggested greater artificially sweetened beverage consumption was associated with a greater presence of symptoms of anxiety.