Regarding "why" RQ is issued; the RQ triggers:
In many respects the effort to discern why RQ has been issued to a particular applicant is at best an academic question, of little practical import, perhaps even a waste of time (if the effort gets bogged down in speculation and wrangling with nuances). Of course there are instances in which the "why" is somewhat if not overtly obvious: a shortfall application, an application containing significant discrepancies either internally or with facts known to CIC, an applicant with NCB red flags in FOSS indicating potential concerns about PR compliance with the Residency Obligation, among some others. But for scores of RQ'd applicants, what triggered the RQ is difficult if not nearly impossible to figure out.
And generally there is no reason to figure out why RQ was issued. Once RQ has been given to an applicant, the applicant's residency is entirely in issue, and the applicant needs to submit proof sufficient to document all time periods declared to have been present in Canada.
Responding to RQ is not at all about responding to the RQ trigger. For example, if RQ was issued because the address on the applicant's drivers license is different from the residential address listed in the application, a entirely believeable response to why that happened is largely irrelevant. Rather, the RQ'd applicant needs to document where he or she was living, working, dates of travel, and existence of other evidence of a life lived in Canada for the full period of time the applicant declared to be in Canada.
That is, there rarely is anything to be gained by spinning one's wheels trying to figure out why RQ was issued.
BUT of course questions about what triggers RQ are really, usually, more about figuring out ways to avoid RQ in the first place.
And this is something CIC does not want prospective applicants for citizenship to know. So CIC conceals, as best CIC can, what the formal criteria are, or how they are interpreted or applied.
I strongly concur in the suggestion to be cautious with the list of risk factors posted above, even though they were specifically the formal triage criteria as of the summer of 2012 and probably constitute the core of what is considered. I concur in the caution precisely because we know, for sure, there have been changes: we know that the criteria have been at the least clarified and subject to certain interpretations, and some probably modified, and some possibly deleted, and perhaps others added.
Moreover, we never really knew more than snippets of internal CIC guidelines or instructions for applying the formal criteria.
That said, the list posted by chikloo is nonetheless a big clue about what CIC examines and considers relative to identifying which applicants it will give RQ.
Dismissing the myth:
(Or, what's luck got to with it? Nothing.)
One widespread misconception is that who gets RQ is largely a matter of luck, or a subjective decision by the individual at CIC who does the triage screening of the application and decides whether a pretest RQ should be sent or not.
Who is issued RQ is not about some vague sense of suspicion perceived by the screener at CIC, although if something is askew or incongruous in the application, arousing suspicion, of course the person doing the screening is far more likely to issue RQ.
There are specific criteria employed by those screening applications at Sydney, and even if at that time nothing triggers RQ, those same criteria are re-examined in the processing of the application at the local office (most notably in the pre-interview check and during the interview). Some of the criteria may be a bit vague, may allow for the exercise of some subjective discretion, but there is a formal list of criteria, and CIC probably has a fairly specific interpretation or approach to applying even those items in that list which seem a bit vague.
The post by chikloo above lists the triage criteria as they were in the summer of 2012, which appears to be based on a copy of the File Requirements Checklist that made its way into the forums back then, which was part of OB 407 issued in April 2012 (and subsequently modified multiple times).
A1 is an illustrative example: A1 - Use of a suspect residential address.
We do not really know, for sure, what this means. What is a "suspect address?"
We know, for example, that CIC has built an inventory of known or identified suspect addresses based on postal codes identified in the investigation of fraud being facilitated by a number of crooked-consultants, supplemented perhaps by other addresses identified as previously used by other applicants determined to have made fraudulent applications. Thus, an application which reflects one of these "suspect" addresses will trigger RQ (RQ plus some I'd imagine, as in an actual, physical investigation focused on the applicant).
For CIC to identify the use of a "suspect residential address" in this sense only requires running the applicant's address(es) against CIC's own database of known or identified suspect addresses. (Telephone numbers are probably, similarly, collected and compared.)
But my sense is that the "suspect residential address" risk factor may be significantly broader than that, and may involve some degree of comparative analysis, be that relative to prior addresses reported by the PR, or conducting directory checks (including Canada411 or Google searches), comparing area codes and pre-fixes in telephone numbers to the address, comparing location of employment to the reported address, perhaps comparing it to the place from which the application was shipped (based on the shipping information on the package the application arrived in), and of course the more obvious comparisons, like comparing it with the address on the applicant's drivers license or other identification submitted. And relative to what the screeners are focused on at any given time, this is probably fluid or dynamic, changing due to the directive-of-the-month for example.
That is, my sense is that the specific risk factors listed as triage criteria probably have, in turn, some further instructional guidelines for identifying what particular facts or circumstances compel checking that item off as an existing risk factor, for the particular applicant, for which RQ is to be issued. And, also, some supplemental directives, from time to time, instructing those doing the screening to focus on this or that in particular. (For example: a directive to those doing the screening to pay particular attention to comparing any handwriting in the application, including signatures in passport and on identification, perhaps including handwriting on the package the application arrived in; then in a different month the focus may be on comparing passport and identification photos.)
My sense is that it is in the guidelines for the respective formally listed criteria that most of the changes to the criteria have been made in the last two years. For example, I'd bet that "self-employed" is still a factor, a risk-factor, but unlike the approach taken in 2012, when the mere combination of any reported self-employment and any travel outside Canada triggered RQ, my sense is that for the applicant who reports a period of "self-employment," there are additional criteria or factors the triage screener considers before determining whether it is a reason-to-question-residency such that RQ will be issued.
Similarly for unemployment.
And, similarly as to C1:
C1 - ID (provided in support of application) has been issued within 3 months of date of application.
Some think C1 has been eliminated from the triage criteria (largely because, I think, some applicants have used such ID and not been issued RQ). In contrast, my sense is that this is a factor which still triggers at least further scrutiny or analysis, and may or may not lead to RQ depending on how other facts and circumstances in the application are assessed along with this factor. (It warrants noting that this has been a risk factor for over a decade, it being one of those expicitly listed as such in the 2005 Operational Bulletin which became an appendix to CP 5 Residence.) I do not know whether CIC somehow distinguishes between renewed forms of identification versus newly issued identification (the latter being a fairly salient signal of a recent arrival, at least at that address if not an arrival in-Canada), or whether there are other contextual considerations employed. Given the history behind this particular risk indicator, however, it seem unlikely it was totally dropped; more likely it is considered in context, sometimes leading to RQ, other times not leading to RQ, again depending.
But overall, for the most part, trying to manipulate all the potential factors which could be considered by CIC in determining who gets RQ, is probably not a worthwhile expenditure of a prospective applicant's time and effort.
OK. I have. I spent many years following CIC's approach to residency, since long before OB 407 and the triage criteria for issuing pretest RQ was employed. But I am a jurist, and early on I was intrigued by the morass of conflicting jurisprudence in which citizenship residency questions were deeply mired. It's been a bit of a hobby.
And sure, what I learned influenced my own approach to applying for citizenship, including avoiding the use of what, back in 2013, were still thought to be poison terms, like "self-employed," and waiting a long while more to apply. (I first met the threshold for 1095 days of actual physical presence by early fall of 2011. I did not apply until summer 2013, nearly two years later, my application arriving in Sydney early in July, 2013.)
And I did not get RQ. I took the oath barely eight months after applying, which was only the second oath ceremony in the city where I live since I submitted my application, the previous one taking place less than four months after I had applied. (In other words, my application went through the process, from submission to oath, as fast as it possibly could given where I live.)
But I would not recommend my approach generally. The effort-to-benefit ratio is dismal. I had other incentives to do the research, and a year after taking the oath I still read every new citizenship case decided and published by the Federal Courts. (And a lot of other decisions involving CIC as well.)
Moreover, the odds it will make a difference are not good. In fact, an attempt to massage the facts in an effort to avoid RQ might be rather transparent and have the opposite effect, inviting questions if not suspicions, tipping the scales toward the issuance of RQ in circumstances where RQ might not have been issued otherwise.
Generally, at least four out of five, probably more like seven out of eight applicants these days, will be processed without being issued RQ. Thus, for the most part there is no need for four out of five qualified applicants to think about or do anything more to avoid RQ than to fill out the application carefully, completely, and accurately, including complete and accurate declarations as to international travel, and have been APP > 1095 days. That is it. And watch eCas and the mail, and prepare for the test.
For the 12 to 15 percent (perhaps less these days) of applicants who are issued RQ (higher percentages were issued RQ in 2011 and even more so in 2012), the majority of these probably could not have done much if anything differently which would have precluded being issued RQ.
Well, sure, perhaps some maneuvers could make a difference; for example, perhaps timing could have an impact (probably did for me). With the effective date for the revised residency provisions looming soon, few are probably contemplating waiting many months longer to apply in order to reduce the risk of RQ.
Always being employed by a readily recognized Canadian employer, working at a recognized Canadian facility, might fare better than a self-employed PR doing consulting for retail marketing in foreign markets. Most such factors, however, are dictated by who we are. It would be foolish to take, or not take, a particular job because of a perceived risk of RQ otherwise. It would be foolish to not move to another province to take advantage of an important career opportunity out of fear it might delay in the processing of a citizenship application.
I am not trying to say the RQ risk factors, the reasons-to-question-residency are irrelevant, not worth considering. For the vast majority of applicants, however, RQ looms as a potential fly-in-the-oinment, but practically is, probably, not going to be their problem, and it is not a reason to expend a lot of extra time or effort, not something which should influence the real-life decision-making immigrants ordinarily make (where to live, when to move, what job to take, and so on).