·
Descriptive statistics
are the appropriate analyses when the goal of the research is to present the
participants’ responses (as frequencies and percentages and/or as means and
standard deviations) 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.
