Suppose you have estimated the following regression: Refrigerator Salesi = ?0 + ?1Pricei + Ui. However, when presenting your results, someone in the audience claims your estimate is biased because your sample only contains sales figures for refrigerators that are priced over $300. Their point is:
A. correct. You have a selected sample on the X variable, so your estimate is biased.
B. incorrect. You have a selected sample on Y variable, but this does not bias your estimate.
C. correct. You have a selected sample on the Y variable, so your estimate is biased.
D. incorrect. You have a selected sample on X variable, but this does not bias your estimate.
Answer: D
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Why is the energy generated from the catabolism of sugars and other macromolecules ultimately harnessed to generate ATP?
A. ATP can be used by cells to drive endergonic reactions B. ATP can be used to make RNA, which is an energy storage molecule in the cell C. ATP synthesis is an exergonic reaction D. ATP is required to generate the proton gradient in the intermembrane space of mitochondria
Which statement regarding porphyrin synthesis pathways is CORRECT?
A. The succinyl-CoA/glycine porphyrin pathway is used by all bacteria, photosynthetic eukaryotes, and archaea. B. The porphyrin biosynthetic pathways are unified at the step of 5-aminolevulinic acid. C. The glutamate porphyrin pathway is used by all non-photosynthetic eukaryotes and alpha-proteobacteria. D. There is very little conservation of porphyrin synthesis pathways between eukaryotes, bacteria, and archaea.
Basal metabolic rate is a measure of the energy required
A. during strenuous exercise. B. at rest. C. during normal daily activities. D. at birth.
Which of the following is typically found in secondary, but NOT primary, cell walls?
a. hemicellulose b. pectin c. cellulose d. lignin