A Researcher Is Trying to Decide Whether or Not to Add

question 31

Short Answer

A researcher is trying to decide whether or not to add another variable to his regression model. He has estimated the following equation for the model from a sample of 28 observations. = 23.62 + 18.86x₁ + 24.72x₂
SSE = 1425
SSR = 1320
​
He has also estimated the model with an additional variable x₃. The results are: = 25.32 + 15.29x₁ + 7.63x₂ + 12.72x₃
SSE = 1350
SSR = 1465
​
What advice would you give this researcher? Use a .10 level of significance.

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Definitions:

NADH

Nicotinamide adenine dinucleotide (NADH) is a coenzyme found in all living cells that is involved in redox reactions, carrying electrons from one reaction to another.

Oxygen

A chemical element (O) that is critical for life, forming about 21% of the Earth's atmosphere and required for cellular respiration in most organisms.

Substrate-Level Phosphorylation

A metabolic process where a phosphate group is directly transferred from a substrate to ADP, forming ATP, without the need for an electron transport chain.

Aerobic Respiration

A metabolic process in which cells convert glucose and oxygen into energy, carbon dioxide, and water.