The confidence interval calculations assume you have a genuine random sample of the relevant population. If your sample is not truly random, you cannot rely on the intervals. Non-random samples usually result from some flaw or limitation in the sampling procedure. An example of such a flaw is to only call people during the day and miss almost everyone who works. For most purposes, the non-working population cannot be assumed to accurately represent the entire (working and non-working) population. An example of a limitation is using an opt-in online poll, such as one promoted on a website. There is no way to be sure an opt-in poll truly represents the population of interest.
Imagine that the selection process is a fair full of stands with products; the product that you are going to promote is yourself, the explanatory brochure is your CV-Resume , the stand of your company is the presentation or resume cover letter (your own) and the competitors are the other candidates who are also using marketing strategies to sell themselves. With so much competition out there, what can you do to make sure that people are interested in reading about your product?
Your Cv-Resume is your primary marketing tool. Cv-Resume purpose is not to get you a job but to get you an interview . Neither an autobiography nor a curriculum vitae, a Cv-Resume presents your relevant skills and accomplishments in an accurate and compelling way to interest potential employers. Your CV Resume is the first stage in finding suitable candidates for a job. Making sure that you make it through to the next round is all a part of how you market yourself on paper. The need to sell yourself in this way is important as your potential employer will make his preliminary judgements based on what he reads, before making that all important decision about whether or not to offer you an interview.