Then there is no significant difference at the stated confidence level. This could be stated as "there is no significant difference between the experimental results and the accepted value for the Standard Reference Materials at the 95% confidence interval."
There is a significant difference between the sample average and the true value if texperimental is greater than tc. tc is chosen for N-1 degrees of freedom at the desired percent confidence interval. If the experimental value may be greater or less than the true value, use a two sided t-score. If specifically testing for a significant increase or decrease (but not both) use a single sided value for tc.
If texperimental is greater than tcritical then there is a significant difference between the two means. tcritical is determined at the appropriate confidence level from a table of the t-statistic for N1 + N2 - 2 degrees of freedom.
P1 sided | t.60 | t.70 | t.80 | t.90 | t.95 | t.975 | t.99 | t.995 |
P2 sided | t.20 | t.40 | t.60 | t.80 | t.90 | t.95 | t.98 | t.99 |
df | ||||||||
1 | 0.325 | 0.727 | 1.376 | 3.078 | 6.314 | 12.71 | 31.82 | 63.66 |
2 | 0.289 | 0.617 | 1.061 | 1.886 | 2.920 | 4.303 | 6.965 | 9.925 |
3 | 0.277 | 0.584 | 0.978 | 1.638 | 2.353 | 3.182 | 4.541 | 5.841 |
4 | 0.271 | 0.569 | 0.941 | 1.533 | 2.132 | 2.776 | 3.747 | 4.607 |
5 | 0.267 | 0.559 | 0.920 | 1.476 | 2.015 | 2.571 | 3.365 | 4.032 |
6 | 0.265 | 0.553 | 0.920 | 1.440 | 1.943 | 2.447 | 3.143 | 3.707 |
7 | 0.263 | 0.549 | 0.896 | 1.415 | 1.895 | 2.365 | 2.998 | 3.499 |
8 | 0.262 | 0.546 | 0.889 | 1.397 | 1.860 | 2.306 | 2.896 | 3.355 |
9 | 0.261 | 0.543 | 0.883 | 1.383 | 1.833 | 2.262 | 2.821 | 3.250 |
10 | 0.260 | 0.542 | 0.879 | 1.372 | 1.812 | 2.228 | 2.764 | 3.169 |
- | ||||||||
20 | 0.257 | 0.533 | 0.860 | 1.325 | 1.725 | 2.086 | 2.528 | 2.845 |
- | ||||||||
inf | 0.283 | 0.524 | 0.842 | 1.282 | 1.645 | 1.960 | 2.326 | 2.576 |