When to use descriptive Statistics to answer RQs


Posted March 4, 2013

Descriptive statistics are the appropriate analyses when the goal of the research is to present the participants’ responses to survey items in order to address the research questions.  There are no hypotheses in descriptive statistics.

·     Descriptive statistics include: frequencies and percentages for categorical (ordinal and nominal) data; and averages (means, medians, and/or ranges) and standard deviations for continuous data.  Frequency is the number of participants that fit into a certain category or group; it is beneficial to know the percent of the sample that coincides with that category/group.  Percentages can be calculated to assess the percent of the sample that corresponds with the given frequency; typically presented without decimal places (according to APA 6th ed. standards).  Typically, the average that is calculated/presented is the mean.  Means describe the average unit for a continuous item; and standard deviations describe the spread of those units in reference to the mean.
·     You cannot (statistically) infer results with descriptive statistics. Inferential (parametric and non-parametric) statistics are conducted when the goal of the research is to draw conclusions about the statistical significance of the relationships and/or differences among variables of interest.
·     Power analyses (sample size and effect size) can be conducted when the analyses used to address the research questions are inferential; not for descriptive statistics and there is not a minimum sample size that is required to conduct descriptive statistics.
·         Descriptive statistics are appropriate when the research questions ask questions similar to the following:
      •  What is the percentage of X, Y, and Z participants?
      • How long have X, Y, and Z participants been in a certain group/category?
      • What are, or describe, the factors of X?
      • What is the average of variable Y?
      • How much do X participants agree about a certain topic?
      • What are, or describe, the similarities and/or differences on a certain topic by group/category?
·     Example: a study was conducted on a group of college students about specific courses offered, where the questions had “check all that apply” responses.  The study’s research question asked “What courses offered to college students are most prevalent?”  Descriptive statistics would be the appropriate analysis to address the research question.  Frequencies and percentages could be conducted on the survey’s listed courses that students took/registered for.  See the table below for details.
Frequencies and Percentages on the Survey’s Listed Courses
Course
n
%
English composition 101
35
25
Chemistry 101
53
66
Algebra 101
16
4
Pottery
2
1
Intro to Psychology
70
85
Art 101
72
86
Note.  Percentages may not total 100 due to rounding error and participant allowance to select multiple responses.

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