Descriptive and Inferential Statistics

This paper introduces two basic concepts in statistics: (i) descriptive statistics and (ii) inferential statistics. Descriptive statistics is the statistical description of the data set. Common description include: mean, median, mode, variance, and standard deviation. Inferential statistics is the drawing of inferences or conclusion based on a set of observations. These observations had been described by the descriptive statistics. From these descriptive statistics, an inference is made subject to a predefined limit or error or confidence interval. The error in concluding the inference is called inferential error. There are two types of inferential errors: (i) Type I error and (ii) Type II error. Type I error occurs when the researcher accepts the alternative hypothesis despite contrary evidence. Type II evidence occurs when the researcher rejects the alternative hypothesis despite supporting evidence.