Issue link: https://www.massageandbodyworkdigital.com/i/68008
The mean duration of headaches during the baseline period was compared with the mean duration during the treatment period … For the group as a whole, mean headache duration decreased from 8.0 ± [plus or minus] 4.3 hours during the baseline period to 4.3 ± 2.3 hours during the treatment phase, and the duration of each headache also decreased for each subject. Because there were only 4 subjects in the study, however, the P value of this measure did not achieve statistical significance (P=.058)."2 All of the participants experienced shorter headaches during the study individually, and in addition, the group's average length of headache duration decreased as well. However, as we discussed in this space in the last issue, because the study had a very small sample size, it had insufficient power to reliably detect a treatment effect. Even though the researchers observed a trend, with a p-value of .058 or 5.8%, that trend was not statistically significant, because it was greater than 5%. Finally, the team examined the effects of their massage protocol [procedure] on the intensity of headaches the study participants experienced: The intensity of the most severe headache that occurred each day was marked on a visual analog scale ranging from 0 to 100 mm (with 100 mm indicating the most severe headache). The mean headache intensities during the baseline period and the treatment period are compared in Figure 3. The effect of massage therapy on headache intensity was subject dependent. Two subjects showed marked improvement, one subject showed mild improvement, and one subject showed an increase in headache intensity. For the group as a whole, changes between the baseline period (44.2 ± 2.2 mm) and the treatment period (35.8 ± 8.2 mm) were not significant for headache intensity as measured by a visual analog scale (P = .19 [19%, or almost 1 time out of 5 that you would see this result by chance]).3 USING STATISTICS, UNDERSTANDING RESULTS These results are fairly straightforward to read in plain language—many articles will present their results that way, while others may use more complicated statistics, numbers, and tables. By practicing and getting more familiar with the statistics commonly used in research studies and the way they are usually presented, you'll start seeing things you recognize, and you'll grow more comfortable with the conventions articles use to present study outcomes. And that's a good thing, because the Results section is often full of tables, charts, and graphs used to present the study's results. In the next article, we'll talk about charts and other graphics—how to build on your developing skills to read them, to understand them, and to interpret them. practitioner and biomedical informatician in Seattle, Washington. She has practiced massage at the former Refugee Clinic at Harborview Medical Center and in private practice. In addition to teaching research methods in massage since 1996, she is the author of an upcoming book on research literacy in massage. Contact her at researching.massage@gmail.com with questions and comments. Ravensara S. Travillian is a massage NOTES 1. M. Hernandez-Reif, Field T, Krasnegor J, Martinez E, Schwartzman M, and K Mavunda, "Children with cystic fibrosis benefit from massage therapy," Journal of Pediatric Psychology 24, no. 2 (April 1999): 175–81. 2. C. Quinn, Chandler C, and A Moraska, "Massage therapy and frequency of chronic tension headaches," American Journal of Public Health 91, no. 10 (October 2002): 1657–61. 3. Ibid. visit massageandbodywork.com to access your digital magazine 129