"Are there better numbers?" is not a question that justifies trusting bad numbers. If the best numbers you have are known to be unreliable, using them just beca

"Are there better numbers?" is not a question that justifies trusting bad numbers. If the best numbers you have are known to be unreliable, using them just because you don't have better ones is not justified. Let's say the real amount per year for the last 10 years is [100, 110, 120, 130, 140], and you have numbers that show [90, 89, 88, 87, 86]. Those numbers are much better than [1, 2, 3, 4, 5]. It would still be absolutely wrong to use them to figure out the trend. If you know your source of data is bad, you must throw it out, even if it's the best one you have. If our data is bad, we just don't know.