OAT Scientific Reading Comprehension 2 — Questions and Answers
Question 1: A passage states: 'The researchers found a statistically significant inverse correlation (r = -0.78, p < 0.01) between intraocular pressure and retinal ganglion cell density.' What does this mean?
- Higher IOP is associated with lower ganglion cell density (Correct answer)
- Lower IOP causes higher ganglion cell density
- The two variables are unrelated
- IOP and ganglion cell density increase together
Correct answer: Higher IOP is associated with lower ganglion cell density
An inverse correlation means as one variable increases the other decreases, so higher IOP is associated with lower RGC density.
Question 2: A study abstract reports a 95% confidence interval of [2.1, 4.3] mmHg for mean IOP reduction. Which conclusion is most appropriate?
- There is 95% probability the true mean reduction is between 2.1 and 4.3 mmHg (Correct answer)
- The sample mean IOP reduction is exactly 3.2 mmHg
- The treatment definitely reduces IOP by more than 4.3 mmHg in all patients
- 95% of patients had reductions between 2.1 and 4.3 mmHg
Correct answer: There is 95% probability the true mean reduction is between 2.1 and 4.3 mmHg
A 95% CI means we are 95% confident the true population mean lies within that interval.
Question 3: A passage describes a double-blind randomized controlled trial comparing two contact lens solutions. The primary advantage of double-blinding in this context is:
- Neither subjects nor evaluators know which solution is being tested, reducing bias (Correct answer)
- Only the subjects are unaware of treatment assignment
- The study uses two separate control groups
- Results can be generalized to all populations
Correct answer: Neither subjects nor evaluators know which solution is being tested, reducing bias
Double-blinding prevents both participants and assessors from knowing treatment assignments, minimizing placebo and observer bias.
Question 4: A graph in a passage shows corneal thickness (y-axis) plotted against age (x-axis) with a shallow negative slope. The most accurate interpretation is:
- Corneal thickness tends to decrease slightly as age increases (Correct answer)
- All older patients have thinner corneas than all younger patients
- Age causes corneal thinning
- Corneal thickness is unaffected by age
Correct answer: Corneal thickness tends to decrease slightly as age increases
A negative slope indicates an inverse trend, but scatter means individual values vary; correlation does not imply causation.
Question 5: A research passage uses the term 'sensitivity' in the context of a diagnostic test for diabetic retinopathy. Sensitivity refers to:
- The test's ability to correctly identify patients who have the disease (Correct answer)
- The test's ability to correctly identify patients who do not have the disease
- The proportion of positive tests that are true positives
- The overall accuracy of the test across all patients
Correct answer: The test's ability to correctly identify patients who have the disease
Sensitivity (true positive rate) measures how well a test detects disease among those who actually have it.
Question 6: A passage states that a new optic nerve imaging device has a specificity of 92%. This means:
- 92% of healthy individuals correctly test negative for glaucoma (Correct answer)
- 92% of glaucoma patients are correctly identified
- 8% of all tests produce false positives
- The device correctly classifies 92% of all patients tested
Correct answer: 92% of healthy individuals correctly test negative for glaucoma
Specificity is the proportion of truly disease-free individuals who receive a negative test result.
Question 7: A passage compares three treatment groups using an ANOVA test with p = 0.03. The correct interpretation is:
- At least one group mean differs significantly from the others at α = 0.05 (Correct answer)
- All three group means are significantly different from each other
- The treatment with the highest mean is significantly better
- The study had a 3% chance of producing these results by random chance alone
Correct answer: At least one group mean differs significantly from the others at α = 0.05
ANOVA tests whether any group means differ; a significant result only indicates at least one difference exists, requiring post-hoc tests to identify which.
OAT Scientific Reading Comprehension 2
A passage states: 'The researchers found a statistically significant inverse correlation (r = -0.78, p < 0.01) between intraocular pressure and retinal ganglion cell density.' What does this mean?