PaulIsclosed

It's not time dependent. If it were time dependent then time would be a covariate, as it's not a covariate you can't say that it's time dependent. Again the time period doesn't matter because he's not using it to conclude that this is the opinion of people now, tomorrow, two weeks ago, at the end of the sample period, at the beginning of the sample period, or anything else BUT the opinion of people during the sample period. It doesn't matter if somebody he sampled changed their mind as he could have randomly selected that person again or somebody else who changed their opinion too. Randomization is necessary, not because we might luck on the perfect sample but because it's required to make rigorour mathematical inference on the data.

Information was not lost because it was not collected as a time series. If they recorded the data and the time that data was obtained but then discarded the time, information would have indeed been lost. However this does not mean the position of the population over that period of time is, or could be inaccurate. As long as the sample was obtained through randomization and that there was still a chance of randomly selecting someone who had already been previously selected then any conclusions drawn from that data over that exact time frame are correct.

There is no dependency on time, it's not a time series. You're missing the point, the sample reflects the position of the population over the period of time that sampling occurred, nothing more. So long as the sampling was randomized then it is not invalidated by the time frame, as it's not purporting to draw conclusions about the position of the population out with the interval of time that sampling took place. If it tried to draw conclusions about the position of the population on any other time interval other than the time interval that sampling took place, then it's conclusions would be invalid.

The data is not a time series so there is no dependency on time, therefore only the conclusions are constrained by that time period and nothing more.

A sample is simply a subset of the population being sampled from therefore as long as it was randomized, the results are valid. I presume you're an engineer and not a mathematician?