sampling, estimation, statistical sampling, sampling plan, judgement sampling, convenience sampling, probabilistic sampling, simple random sampling, systematic sampling, periodic sampling, stratified sampling, cluster sampling, sampling from continuous processes, estimation, estimator, point estimate, sampling error, non-sampling error, representative sample, sample sample, biased estimate, self-selection bias, sampling distribution of the mean, standard error of the mean, interval estimate, confidence, confidence level, alpha, degrees of freedom, central limit theorem,