Why is establishing a standard curve critical in protein measurement techniques?

A standard curve lets you translate the signal you get from a protein assay into an actual amount of protein, because the signal alone is meaningless without a reference. By measuring known amounts of a protein and plotting the signal versus concentration, you create a line that shows how the signal grows with concentration. When you test an unknown sample, you compare its signal to this line and read off the concentration directly. Without this curve, you cannot convert the raw data into a quantitative result, so the measurement would be vague and unreliable. For example, if a 10‑µg/ml protein gives a 200‑unit signal, the curve tells you that a 400‑unit signal corresponds to 20 µg/ml, allowing precise quantification.