An interviewer observed babies born with birth defects and babies born without birth defects in the years between 2010 to 2015. He selected twenty mothers of babies born with birth defects for questioning to form Group A. He also selected twenty mothers with healthy babies for questioning to form Group B. The goal of the research is to study the impact of environmental toxins on birth defects. He printed forty pamphlets with questions and gave one pamphlet to each mother to fill out. The questions are written to lead all mothers to write down their views on the health of their babies. After the study, the interviewer realized that mothers of babies born with birth defects searched their memories more thoroughly than mothers with healthy babies. Which is the most obvious bias in this study?

A 56-year-old woman presents to her primary care physician with complaints of painless hematuria, which she first noticed two months ago. She describes the hematuria as intermittent but more pronounced over the past week. She denies dysuria, urinary frequency, or urgency. There is no associated flank pain, fever, or weight loss. Her past medical history includes hypertension, managed with amlodipine, and she has no family history of malignancy. However, she reports a significant smoking history of 30 pack-years, having smoked one pack of cigarettes daily since her early twenties. A cystoscopy reveals a 3 cm papillary tumor on the posterior wall of the bladder, and transurethral resection of the bladder tumor (TURBT) confirms the diagnosis of urothelial carcinoma. The physician hypothesized that her smoking history of 30 pack-years contributed to her bladder cancer. His hypothesis later found to be consistent. Which of the following is an example of the Bradford Hill criterion of “consistency”?

A 50-year-old male, living in an industrial urban area, presents to his primary care physician with a persistent cough, shortness of breath, and wheezing over the past year. He has no history of smoking, occupational exposure to irritants, or significant family history of respiratory illnesses. Upon further questioning, it is revealed that he has been exposed to high levels of air pollution due to residing near a factory emitting fine particulate matter (PM2.5). The physician hypothesizes that chronic exposure to air pollution may be contributing to his respiratory symptoms. To establish a causal relationship between air pollution and respiratory disease, the Bradford Hill criteria are applied. What does the criterion of “biological gradient” refer to in the Bradford Hill framework?

A 48-year-old male, living in an industrial urban area, presents to his primary care physician with a persistent cough, shortness of breath, and wheezing over the past year. He has no history of smoking, occupational exposure to irritants, or significant family history of respiratory illnesses. Upon further questioning, it is revealed that he has been exposed to high levels of air pollution due to residing near a factory emitting fine particulate matter (PM2.5). The physician hypothesizes that chronic exposure to air pollution may be contributing to his respiratory symptoms. To establish a causal relationship between air pollution and respiratory disease, the Bradford Hill criteria are applied. Which of the following Bradford Hill criteria is considered essential for establishing causality?

A new screening test ‘Rapidpox’ was developed to detect monkeypox and used in conjunction with confirmatory tests to determine its statistical parameters in a population of 1050 individuals. The screening test gave a positive result in 120 individuals who were later determined to have the monkeypox by confirmatory testing. It gave positive results in 10 individuals who were later determined to not have the monkeypox by confirmatory testing. On the other hand, it gave negative test results in 20 individuals who were later determined to have the monkeypox by confirmatory testing. Additionally, it gave a negative test in 900 individuals who were later determined to not have the monkeypox by confirmatory testing. What is the positive predictive value of this new screening test for monkeypox?