The phrase "a long response" is correct and usable in written English.
You can use it when referring to a reply or answer that is extensive in length or detail.
Example: "I appreciate your patience; here is a long response to your question about the project."
Alternatives: "an extended reply" or "a lengthy answer."
[Oct. 18, 10 59 a.m. | Updated | John Rennie has filed a long response to this piece.
AFTER our story last week on AIG, Sanford Bernstein, a Wall Street research house, issued a long response (click here for excerpts from its response).
Richard Morse, an analyst of coal markets, climate policy and China at Stanford University, offered a long response to Pope's thoughts and the initial discussion of coal exports that is also posted separately.
| Updated | Sandra Steingraber has sent a long response to my question about the definitiveness of the language she used in the letter to Gov. Cuomo to describe breast cancer trends in the Barnett Shale region of Texas.
Piketty wrote a long response in which he defended his book, although he also conceded that "available data sources on wealth inequality are much less systematic than what we have for income inequality".
So, Lawrence Freedman rightly asked Blair whether it was honest to publish a dossier which said Saddam had weapons of mass destruction that could be launched at 45 minutes' notice – when, in fact, that figure referred to short-range, battlefield munitions – and was treated to a long response that contained no answer, barring an admission that he hadn't "really focused" on it.
We designated this question as a long-response question because a correct answer necessarily involved more than one sentence.
Fig. 4 Histogram of the change in number of principles of natural selection provided by students in a long-response item, before and after instruction.
Fig. 5 Difference between advanced and beginner student use of principles of natural selection in a long-response item, before and after instruction.
For example, a question about "particular problems" Google has faced in implementing the ruling yields a page long response from Mountain View — with Google waxing lyrical on the difficulties of balancing competing interests when making the judgements.
