Statistics - Descriptive statistics 2013/09/23

Data and statistics Statistics is the art of collecting, analyzing, presenting, and interpreting data. – Application (Marketing, …) Data are the facts and figures collected, analyzed, and summarized for presentation and interpretation. – P5. Table 1.1

Data and statistics Data collection requires one of the following scales of measurement: – Nominal – Ordinal – Interval – Ratio Data can also be classified as: – Qualitative – Quantitative

Data and statistics Descriptive statistics: – Data are often summarized and presented in a form that is easy to understand. Such summaries of data, which may be tabular, graphical, or numerical, are referred to as descriptive statistics. Statistical inference: – Statistics uses data from a sample to make estimates and test hypotheses about the characteristics of a population through a process referred to as statistical inference.

Descriptive statistics Summarizing qualitative data – Tabular methods Frequency distribution (P28. Table 2.1 & P29. Table 2.2) Relative frequency distribution (P29. Table 2.2 & Table 2.3) Percent frequency distribution (P29. Table 2.2 & Table 2.3) – Graphical methods Bar graph (P29. Table 2.2 & P30. Figure 2.1) Pie Chart (P29. Table 2.3 & P30. Figure 2.2)

Descriptive statistics Summarizing quantitative data – Tabular methods Frequency distribution (P34. Table 2.4 & P35. Table 2.5) Relative frequency distribution (P34. Table 2.4 & P36. Table 2.6) Percent frequency distribution (P34. Table 2.4 & P36. Table 2.6) Cumulative frequency distribution (P34. Table 2.4 & P38. Table 2.7) Cumulative relative frequency distribution (P34. Table 2.4 & P38. Table 2.7) Cumulative percent frequency distribution(P34. Table 2.4 & P38. Table 2.7)

Descriptive statistics Summarizing quantitative data – Graphical methods Dot plot (P36. Figure 2.3) Histogram (P37. Figure 2.4) Ogive (P39. Figure 2.6) Stem-and-leaf display (P44. Table 2.8) Scatter diagram (P52. Table 2.12)