Of course you haven't established 'statistical significance' with such differences and so few replicates. Were you trying to? That is what
CATRA is for - high volume automated testing of slicing edge retention. I thought that you were simply assessing general properties, i.e. trends, not looking for statistical significance. Is it necessary to do so?
For the purposes of knife-steel, properties like edge-retention and impact toughness allow general categorization of the steels - high/mid/low wear, high/mid/low toughness. For impact toughness, most high-chromium steels at knife-blade hardness (i.e. 58-60 Rc) can endure 20-30 J/cm2 up to ~40 with PM or very fine grains; whereas tools steels like O1 & A2 tend to reach from 40 to 70; and high-toughness steels breach 100 J/cm2. For wear-resistance, even CATRA tends to categorize knives/steels rather than rate individual performance because measurement variability is so high. "Amateur" Ankerson here on BF gives ~10 categories or wear-resistance for his testing.
When companies market their steels, they prefer comparative bar-charts of relative values to actual measured values because they know that the measurements have little 'real-world' meaning. The specific value is less important than the general range of endurance. Statistical significance isn't necessary for generalizations, and generalizations are all that is necessary to demonstrate capacity. In summation, don't be too hard on yourself! This is great work and demonstrates what
you are capable of with these steels as well as showing where you can improve.
Now, the degree of variance in your most recent test is still a matter of concern because it doesn't even show a trend. Given our method, a variation +/-20 is quite consistent, +/-40 somewhat less so, >40 is pushing it. Remember that your method tests how intact the
very edge of the knife is, something that drops away
very quickly in the stabilization process. Others have performed tests like this on literally thousands of knives or the same knife dozens if not hundreds of times in order to accrue a trend-line of edge-loss that is 95% confident. You don't want to waste time doing that. Keep up the good work, and stabilize that second set a little :thumbup: