Wikipedia:No original research/sandbox

Synthesis of published material
Do not combine material from multiple sources (or different parts of one source) to reach or imply a conclusion not explicitly stated by any of the sources. This would be improper editorial synthesis of published material to imply a new conclusion, which is original research performed by an editor here.

For example, if one reliable source says A, and another says B, do not join A and B together to imply a conclusion C that is not mentioned by either of the sources.  Example:

Although no conclusion is explicitly drawn and both parts of the sentence may be reliably sourced, they have been combined to imply that the UN has failed to maintain world peace. If no reliable source has combined the material in this way, it is original research. It would be easy to imply the opposite using the same material, illustrating how material can easily be manipulated when the sources are not adhered to:

Similarly, "A and B, therefore C" is acceptable a reliable source has published the same argument in relation to the topic of the article.  Example:

The following is a more complex example of original synthesis, based on an actual Wikipedia article about a dispute between two authors, here called Smith and Jones. The first paragraph is fine and properly sourced:

Now comes the original synthesis:

The second paragraph is original research because it expresses a Wikipedia editor's opinion that, given the Harvard manual's definition of plagiarism, Jones did not commit it. To make the second paragraph consistent with this policy, a reliable source would be needed that. In other words, that precise analysis must have been published by a reliable source in relation to the topic before it can be published on Wikipedia.