2022 Introduction to Statistics in Research Mitchell 2nd ed

I N T R O T O R E S E A R C H : D A T A V I S U A L I Z A T I O N & C O M M O N S T A T T E S T S

Deciding an appropriate statistical method must also consider what is the main research question, but for now, let’s look at the ways to describe and visualize the data.

Nominal scale describes the variable with categories.

Example of nominal variables : zip code, eye color, political party

“ Ordinal scales represent rankings that have magnitude, but we do not assume that the intervals between the rankings are equal. Because we do not assume equal intervals with ordinal data, we do not calculate the mean and standard deviation” (Adams & McGuire, 2022, p. 15 4).

Example of ordinal variable : social economic status – low income, middle income, high income Another example: satisfaction rating (extremely dislike, dislike, neutral, like, extremely like)

“ Interval scales are ratings in which we assume there are equal intervals between scores …, do not have a true zero” (Ibid, p. 154).

Example of interval variable : SAT Score (200-800), Credit score (300-850)

“ Ratio scales measure quantity and have both equal intervals and a true zero” (Ibid, p. 154).

Example of a ratio variable : pulse, weight, dose amount

OK to compute….

Nominal Ordinal

Internal

Ratio

Frequency distribution , percentages, describing places or rankings

YES

YES

YES

YES

Median and percentiles

NO NO

YES NO

YES YES

YES YES

In normal distribution: Mean, standard deviation, standard error of the mean If skewed data*, median, interquartile range

NO NO

NO NO

YES NO

YES YES

Ratios, coefficient of variation

Table 76: Table modified fromGraphPad, Article #1089 (2019, Oct 03)

* A big difference between the mean and the median indicates skewed data or influential outliers.

Besides the graphical displays to help us understand our data, this chapter also covers benchmarking and the introduction of data analytics to communicate trends.

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