"That my results are not reproducible" or "that my results are unreproducible"?

Solution 1:

I would usually say not reproducible, and if I wanted to use a single word I would always use irreproducible rather than unreproducible.

Solution 2:

First part: “not reproducible” seems to be widely more used than “unreproducible”. I checked this on Google, the Corpus of Contemporary American English, the British National Corpus, and a Google search restricted to a scientific publisher website (American Chemical Society, acs.org).

Second part: it's hard to say something this negative with a very positive tone. One way to make it more positive is to hint at possible reasons why you could not reproduce the results, e.g., “my results could not, under the time available, be reproduced”.

Solution 3:

that my results are non-reproducible

Both the prefixes un- and non- have the same meaning, but they are used with different perspectives.

In a note, the NOAD reports that

The prefix un- tends to be stronger and less neutral than non-. Consider, for example, the differences between unacademic and nonacademic, as in his language was refreshingly unacademic, and a nonacademic life suits him.

Solution 4:

It is unclear what context the original poster is considering, but it should be mentioned that both examples given have a strong implication that the results are, in principle, incapable of being reproduced.

A "positive alternative" without this implication would be something like "the results have not yet been reproduced" or "my colleague was not able to reproduce the results"