how does a double blind experiment work

HESI LPN

LPN Nutrition Practice Test

1. How does a double-blind experiment work?

A. Both subject groups take turns receiving each treatment.
B. Neither subjects nor researchers know which subjects are in the control or experimental group.
C. Neither group of subjects knows whether they are in the control or experimental group, but the researchers do not know.
D. Both subject groups know whether they are in the control or experimental group, but the researchers do not know.

Correct answer: B

Rationale: The correct answer is B. In a double-blind experiment, neither the subjects nor the researchers know which subjects are in the control or experimental group. This helps to eliminate bias and ensure that the results are more objective. Choice A is incorrect as in a double-blind experiment, subjects do not take turns receiving each treatment; it is about masking the treatment allocation. Choice C is incorrect because it implies that the researchers are aware of the group allocation, which goes against the principle of blinding in a double-blind study. Choice D is incorrect as both subject groups should not know whether they are in the control or experimental group to maintain the blindness of the study.

2. In what position does the Pavlik harness hold a child's femurs for developmental hip dysplasia?

A. Abduction
B. Adduction
C. Flexion
D. Extension

Correct answer: A

Rationale: The Pavlik harness is designed to position a child's femurs in abduction for developmental hip dysplasia. Abduction helps align the hip joint correctly and promotes proper development in cases of hip dysplasia. Adduction (choice B) brings the legs closer to the midline, which is not the desired position in this condition. Flexion (choice C) refers to bending at a joint, while extension (choice D) is the opposite of flexion. However, in the case of developmental hip dysplasia, abduction is crucial for the Pavlik harness to work effectively.

3. Which lab result should be abnormal in a child with hemophilia?

A. Prothrombin time
B. Bleeding time
C. Platelet count
D. Partial thromboplastin time

Correct answer: D

Rationale: In a child with hemophilia, the lab result that should be abnormal is the partial thromboplastin time (PTT). Hemophilia is a disorder that affects the clotting factors in the intrinsic pathway of coagulation, leading to a prolonged PTT. Prothrombin time (Choice A) assesses the extrinsic pathway and should be normal in hemophilia. Bleeding time (Choice B) evaluates platelet function, which is typically normal in hemophilia. Platelet count (Choice C) measures the number of platelets and is not directly affected by hemophilia.

4. What is a key aspect of managing a child with cystic fibrosis?

A. Regular pulmonary function tests
B. Daily administration of antibiotics only
C. High-sugar diet
D. Limiting all physical activities

Correct answer: A

Rationale: Regular pulmonary function tests are a key aspect of managing a child with cystic fibrosis. These tests help monitor lung function and disease progression effectively, providing valuable information for healthcare providers to make timely interventions and adjustments to treatment plans. Daily administration of antibiotics alone (Choice B) is important but not the sole key aspect of managing cystic fibrosis. A high-sugar diet (Choice C) is not recommended for individuals with cystic fibrosis as it can exacerbate health issues. Limiting all physical activities (Choice D) is not beneficial as regular exercise is important for overall health and lung function in individuals with cystic fibrosis.

5. A weight reduction regimen calls for a daily intake of 1400 kilocalories, which includes 30 grams of fat. What percentage of the total energy is contributed by fat?

A. 8.50%
B. 15.00%
C. 19.00%
D. 25.50%

Correct answer: C

Rationale: To calculate the percentage of total energy contributed by fat, first determine the energy from fat by multiplying the fat amount (30g) by the energy density of fat (9 kcal/g), which equals 270 kcal. Then, divide the energy from fat (270 kcal) by the total energy intake (1400 kcal) and multiply by 100 to find the percentage: (270 kcal / 1400 kcal) * 100 = 19.29% ≈ 19.00%. Therefore, fat contributes approximately 19% of the total energy in the diet. Choice A (8.50%) is too low, while choices B (15.00%) and D (25.50%) are incorrect calculations based on the given information.