Purdyd,
Wow, someone has actually read my report! Thanks for catching that. I guess I made an error in transcribing my data on that one comparison. I entered a “4†when I should have entered a “3â€. It actually made quite a bit of difference in judging the significant dullness of the knife. Here are the corrected calculations, showing that indeed, there is a significant difference at the .05 level. Intuitively, I did feel that there should be a difference in sharpness, when I looked at the data, and saw that , for the first time, 2 samples showed a 3 kilogram force reading. I am glad that you went with a stronger intuition, and looked more closely, than I did.
Here is the corrected comparison analysis for the 2 dates.
RESULTS OF THE t-Test: Using the following:
CONTROL group ( date: 11-21-07) Summary Statistics
sample value of the group Mean = 2.3475
sample value of the group Standard Deviation = .1936
sample size for group n = 4
COMPARISON group (date: 10-10-08) Summary Statistics
sample value of the group Mean = 3.015
sample value of the group Standard Deviation = .2453
sample size for group n = 4
Results of the t-test for 11-21-07 compared to 10-10-08
The difference between 2.347 and 3.015 (not the previously entered 4.015) with standard deviations of .1936 and .2453 based on sample sizes of 4 and 4, respectively, is significant at the .05 level. The value of the t-statistic for this test was -4 . 28.
Thanks again for reviewing my calculations, and alerting me to the fact, that, after 11 months of use, there has been a detectable change in the sharpness of my knife, and that, if I wish to carry a hook knife, which has a relative sharpness to a new knife, that, … it is time to change my hook knife.
Thanks for being my “second pair of eyesâ€.
By the way, I agree with you, that carrying 2 hook knives is better than carrying only one. I carry a little double bladed knife in my helmet pocket, and a large one in my spreader bar pad.