APA Style: Reporting Statistical Results - Pindling.org

1 Tony s Research: Appendix E APA Style: Reporting Statistical Results 1 Appendix E APA Style: Reporting Statistical Results Central Tendency Standard Deviation 2 Introduction Most behavioral or social science and educational research journals uses guidelines from the American Psychology Association (APA) outlined in the Publication Manual of the American Psychological Association (2001). When cited in a journal, it is reported as (APA, 2001). All Statistical symbols are reported in italics: N, SD, M, p, Mdn, r, df, etc. This is true whether they appear in the body of the journals or tables. This section covers specifically how APA style is used to report Statistical information or Results in various forms in a journal. A smaller font size (10) will be used in this section to indicate how a narrative textual reference is made on or about a particular statistics.

2 All illustrations in this section conform to the APA style. Central Tendency Measures of central tendency are reported in APA style using the symbol M for mean and Mdn for median. There is no symbol for mode. Rarely is mode reported, mean or median is preferred. Reporting the mean in the body of the journal may look like The pretest score for the group is lower (M = ) than the posttest score (M = ). The full name of the statistics may also be used in describing it in a narrative text. Here is an example statement about the median of two categories: The median study time for the treatment group was hours, compared to a median of for the control group. When there are many means or medians to report, tables with appropriate headings or graphs may show these simultaneously. Table shows the means of both the pretest and posttest scores for male and females on an aptitude test.

3 Notice that the statement about the mean being summarized in this particular table is presented in the table title. Later, you will see how various symbols for central tendency are used within tables. 3 Table The Mean Scores for Pre- and Posttest by Gender Pretest Posttest Female Male When graphs are used to represent many central tendency Results , a polygon or line chart may be used to represent continuous dependent variables. A continuous line is used to connect the different categories or levels within a category of independent variables being used. Figure shows a polygon of the mean number of correct responses to questions from a group of subjects at midnight and several hours afterwards. 05101520253035012345 Hours after MidnightMean Correct Responses Figure Mean correct responses at midnight and various hours afterwards An alternative to the line chart or polygon is the histogram.

4 Both the polygon and histogram may be used to show summary of many mean or median Results at various 4 levels of an independent variable. The mode is rarely summarized in these graphs. When numbering both the X-axis and Y-axis of any chart, start with zero at the intersection of the two axes as in Figure This helps avoid any visual misrepresentation of graphical comparisons. Figure shows a histogram of the mean number of correct responses to questions from a group of subjects during weekdays. 051015202530354045 MondayTuesdayWednesdayThursdayFridayWeek daysMedian Correct Responses Figure Median correct responses by weekdays Standard Deviation Descriptive statistics on dependent variables involving all scales of measurement except nominal, often report both measurements on central tendency and variability together.

5 In APA style, the symbol for the standard deviation is SD. The Results of a Statistical summary may include the following texts about descriptive statistics: The pretest score for the group is lower (M = , SD = ) than the posttest score (M = , SD = ). 5 When Reporting the descriptive Statistical summary of many groups, the Results may be summarized in a table. Table shows the means and standard deviations of the mean responses of subject to two treatments for several groups on an aptitude test. Notice that the descriptive statistics symbols are used in the body of the table. Table also shows the sample size, N. Table The Descriptive Statistics for each Treatment by Groups Treatment 1 Treatment 2 M SD N M SD N Group A 16 14 Group B 20 18 Group C 15 12