There are slight differences in the meanings of these terms, but they are often used interchangeably. 1  Independent Variable: It implies causality: the independent variable affects the dependent variable. 2  Used predominantly in ANOVA, but often in regression as well. 3  It can be either continuous or categorical.
Protein Quality. Collagen is not a complete protein because it is lacking in the amino acid tryptophan. A Protein Digestibility Corrected Amino Acid Score (PDCAA) of a complete protein is 1.0.ollagen is a protein found in the muscle and connective tissue of animals. Hydrolyzed collagen protein supplements are typically made from the bones and skin of cows, horses or pigs.
Updated November 30, 2016. Collagen is a protein made up of amino acids that is found in the human body. Here's a look at what collagen is and how it is used in the body. Like all proteins, collagen consists of amino acids, organic molecules made from carbon, hydrogen and oxygen.