Research Validity
This aspect of data gathering may be quite complex to the non-researcher. Very basically however, validity is whether the research is actually measuring what it claims to be measuring. Therefore it is a good idea to know how the research was undertaken and if this is really measuring what you wanted it to measure. If you have any fears about whether this is true, it is possible the results of the survey should be called into question.
Research Reliability
This problem relates to whether research results can be applied to a wider group than those who took part in a study, also called generalization. In short, if another group of respondents was used would the results be similar? And therefore, can your results be generalized out to represent a larger population than your sample size?
Reliability is chiefly concerned with generating consistent results, this can be done for instance by having two researchers question the same number of people from a sample and if the responses are similar it is likely the results are good and can therefore represent a wider population.