2/21/2022 Types of Data Types of Data Qualitative (or non-numeric) Qualitative (or non-numeric) Can't use meaningfully in a computation... Can you take the average of the observed political affiliations? No, it's non-numerical. e.g. Dem, Dem, Rep, Ind, Dem, Rep... Non-numerical in nature (but could be 'coded' as a number, so be careful). Could be considered a label in some cases. Average ID #? ID #s 56, 213, 788,... no. If variable is represented by numbers (as with IDs), ask yourself if an average makes sense... # 90 isn't "larger than" # 45 in the mathematical sense. They're just a label. if not, then it's qualitative not quantitative. Quantitative Datu Type Level of Measurement Nominal Can be shown with a distribution, or summarized with an Qualitative average, etc. Commonly used summaries: Average value Ordinal Qualitative data is either Nominal or Ordinal (only 2 options) Interval Maximum or Minimum value Ratio Standard deviation (a measure of spread of the data) Quantitative Interval Continuous Summarizing a distribution with a single value can be very useful. But be aware that 'averaging' (or pooling, or aggregating) can potentially hide some interesting information. Ratio Levels of Measurement for Qualitative Data Levels of Measurement for Qualitative Data Political affiliation (dem, rep, ind)- Nominal Level of pain (low, med, high)- Ordinal Two levels Nominal level (by name) No natural ranking or ordering of the data exists. Answer to survey: strongly disagree, disagree, agree, strongly agree Ordinal level (by order) Provides an order, but can't get a precise mathematical difference between levels. Could be coded numerically, so again, be careful. Ordinal Eye color: blue, green, brown, etc. Nominal 2 3. 2/21/2022 ad1, Level of Measurement Two kinds of Quantitative Data Nominal Qualitative Continuous Can take on any value in an interval Ordinal Could have any number of decimals Discrete Quantitative Ratio Interval Continuous Discrete Ratio Can take on only particular values Quantitative data can be either Discrete or Continuous and either Interval or Ratio Levels of Measurement for Quantitative Data: Interval or Ratio? Levels of Measurement for Quantitative Data: Interval or Ratio? Interval level (a.k.a differences or subtraction level) Interval level (a.k.a differences or subtraction level) Intervals of equal length signify equal differences May initially look like a qualitative ordinal variable (e.g. low, med, high), but levels are quantitative in nature and the differences in levels have consistent meaning. in the characteristic Scale for evaluation: Differences make sense, but ratios do not. If a change from 1 to 2 has the same strength as a 4 to 5, then we would call it an interval level measurement (if not, then it's just an ordinal qualitative measurement). Occurs when a numerical scale does not have a 'true zero' start point (i.e. it has an arbitrary zero). KAo Levels of Measurement for Likert scale (sometimes unclear) Quantitative Data: Interval or Ratio? Is it Interval (Quantitative) or Ordinal (Qualitative) scale? Ratio level (even more meaning than interval level) At this level, both differences and ratios are meaningful. Most of the time, these surveys are just ordering responses lowest to highest and NOT fulfilling the interval scale requirements. -Difference of opinions on this though. Website Uner Survey Occurs when scale does have a 'true zero' start point. 1. Phe welcie ha r r isterfae enla Ratios involve division (or multiplication) rather than addition or subtraction.