6 ms·

The answer has to be A, under reasonable assumptions. If you assume that the university wants to find out the opinions of all students, and if you assume that

• ghaff 4y ago
  Right, you also don't know what was covered in the class. But do the best you reasonably can to collect a random sample and then go with it is almost certainly the best answer in this case. (Although you can make an argument for D.)
• deleted 4y ago
  [deleted]
• tedmiston 4y ago
  "Has to be" is a stretch. By nagging the non-respondents you are introducing a bias that the first group of respondents were not exposed to. If you annoy a respondent, it's very reasonable to assume that can influence their responses (probably negatively). Option D seems objectively better to me over Option A based on this bias.
  • cat_plus_plus 4y ago
    Option A is strictly superior to option D, as you are still have the data for original 90 responses. If second round responses are similar, you have increased confidence that you are not running into responder bias. If it's different, you can publish both and note uncertainties and need for further study.
    • tedmiston 4y ago
      I hear your argument, but that also introduces a slippery slope of cooking the data to support your original hypothesis. Now that you have the original data set and the expanded data set, one is likely to do that better than the other. If the research industry were as pure as science itself of course that would never happen...
• silisili 4y ago
  I actually vote against A. My work was always sending out 'completely anonymous' surveys that I generally ignored. Resending to tell me I hadn't done it yet was indication enough to me that it wasn't completely anonymous at all. While the question doesn't mention anonymity specifically, I'm sure it remains a point in some percentages mind.
  • nh23423fefe 4y ago
    But I could make a table Request(email, url, submitted) and a table Response(data) And you couldn't connect the response to the user. Thats the important part right? not the ability to resend a request
    • silisili 4y ago
      I'd argue recording anything at all, including whether I did it, breaks the 'completely anonymous' contract. Then we're left with...mostly anonymous. But at that point it's a black box. It could be done how you describe. Or it could be attaching my name to the survey and emailing the CEO directly. I'd never know the difference.
      • nh23423fefe 4y ago
        I mean sure. If you think someone is lying to you then it doesn't matter. But I disagree with "getting a reminder means its not anonymous" its completely orthogonal.
    • jayd16 4y ago
      Are you assuming the request to respond is broadcast to all recipients regardless of response status?
      • nh23423fefe 4y ago
        No implementation is something like email is primary key, url is per user. going to page and submitting will do two things. the table Request will be updated and marked submitted. the table Response will be populated with only the data.
• charcircuit 4y ago
  The people who didn't represented when nudged can answer incorrectly because they are just trying to speed through it. It should be treated as a separate population and not merged into the rest.
  • ToJans 4y ago
    This is how we do it in reality. Missing answers are very important!
• panny 4y ago
  >The answer has to be A We have this problem at work. You try to contact customers and they never respond. Sending repeated queries has no effect. The real answer is: The question is poor and ambiguous, therefore the question is wrong. It reflects poorly on the academic institution asking it. I would be in search of a new school for my child if I saw many test questions like this. They didn't even enumerate the answers correctly. It is asking for the best plan of action for the University without clearly specing out the goal and all its parameters. The goal may be "Determine if at least half of our first year students had a positive experience." and that can possibly be solved with 90 responses if at least 60 had positive experiences. It's just like when your boss asks for a time estimate on a task he's barely defined. It depends on the spec he's asking from you. Without clear specification, the question isn't answerable.
  • defrost 4y ago
    > It reflects poorly on the academic institution asking it. Only in so far as it is posed with a multiple choice response and no opportunity to make a comment. The question itself is about a commonplace occurrence in statistical sampling.
    • panny 4y ago
      >The question itself is about a commonplace occurrence in statistical sampling. It certainly is, but once again, the question does not specify enough information to choose an answer. Maybe A is correct, if you have a backup/secondary email to try. Maybe, like so many of us who work with email notifications, they can see the email wasn't opened. Or it bounced. Or it was opened and flagged as spam. Is that all the information you have? You emailed 120 of them and received 90 clickthroughs? Well sir, that is an astounding clickthrough rate! Perhaps that exceeds every expectation of responses and is itself actionable. Perhaps the best plan of action for the University is to discover their magic clickthrough sauce and monetize it. What is the best plan of action? Impossible to answer when they haven't specified a goal.
      • defrost 4y ago
• jandrese 4y ago
  I have no reason to believe that students that ignored the survey the first time would respond to a second survey. There will always be non-respondants, it's just part of the domain. I'd vote for sending out 120 more surveys simply because 120 is a very small sample size to begin with.
  • pjscott 4y ago
    There’s always a risk that if you increase sample size without addressing selection bias, you’ll just end up with more confidence in an incorrect conclusion. (“Dewey defeats Truman!”)
• TheOtherHobbes 4y ago
  Two fallacies: 1. The non-responders are not responding for similar reasons. 2. Those reasons are somehow related to their opinions. Both are clearly false. You cannot assume anything about their opinions from the fact that they didn't respond. All you have is their (non)action - which could have been caused by being ill, busy, distracted by personal issues, absent, drunk, or for any other number of reasons. None of the answers are correct. If you wanted representative data you would have to: 1. Confirm with a different sample but also... 2. Use multiple different channels and methods (phone, in-person survey on campus, maybe an email survey with some kind of benefit to encourage participation, etc) to try to eliminate the non-responders who have personally valid but statistically irrelevant reasons (away, ill, etc).
  • wheats 4y ago
    As the blog post says non-responders do tend to have different opinions on average than responders. Typically they do try to demographically determine who those non-responders are so they can adjust and increase the weight of that group proportionally to their limited response. This is how most polling works in the real world and it does provide better accuracy.
  • tgv 4y ago
    Suppose the non-responders are identical to the responders. Then nothing is lost by trying to get them to participate again. But if they are not, replacing them will lose information. > ill, busy, distracted by personal issues, absent, drunk But being ill correlates (lightly) with being older, and being drunk heavily correlates with opinions. Being absent might correlate with wealth (and not even linearly). Personal issues probably correlate with education. Add them together, and you've got a fairly large part of the population missing from your sample.
• pdonis 4y ago
  > Only choice A tries to solve this problem. No, it doesn't. It doesn't get any information from non-responders; it can't, because they don't respond! It only gets information from some people who respond on the second try instead of the first.
  • next_xibalba 4y ago
    There is nothing in the question which suggests some of them (or all) wouldn't respond to a second, third, or nth prompt. In many surveys, non-respondents receive multiple outreach attempts.
    • pdonis 4y ago
      > There is nothing in the question which suggests some of them (or all) wouldn't respond to a second, third, or nth prompt. Of course not. But making second, third, or nth requests is not "sampling from non-responders". It's just creating more and more different groups of responders. Which doesn't improve anything statistically that I can see; in fact it might make things worse, because you are introducing more and more potential confounders.
      • psyklic 4y ago
        When this is a concern, I do two analyses -- one with and one without the potentially confounding group. It is still better to obtain the data, since otherwise we knowingly have a biased sample. (Somewhat similar to only surveying people who "seem approachable.")
        • pdonis 4y ago
          > When this is a concern, I do two analyses -- one with and one without the potentially confounding group. If this analysis tells you there is no significant difference between the subgroups, that's nice, because you can then just lump them into one and not worry about it any more. (This also tells you you didn't actually need to send out the second email, but what's done is done.) But if this analysis tells you there is a significant difference between the subgroups, you don't know if it's something that was there already or something that you created by sending out a second email to people who had not responded to the first. So you're not actually better off than if you hadn't sent the second email; you're worse off, because you now have a confounding variable present and you don't know what to do about it. > otherwise we knowingly have a biased sample You have a biased sample regardless of whether you send out a second email or not.
• AtlasBarfed 4y ago
  No, the question says the original 120 were "sampling". There is no "all".
• aj7 4y ago
  Option A is absolutely the worst choice. The non-responders have already selected themselves into a non-random set, and making a request to them alters the entire experiment.
  • quickthrower2 4y ago
    Surely the responders are also self selected into a non random set too?
    • aj7 4y ago
      The set you wanted, so IN the experimental design. Or did the experiment include also begging people to fill out a questionnaire they had initially trashed? Many people appear to think so.