PART II: THESIS MANUSCRIPT
2.4 Data Analysis
The data collected from the Qualtrics program was first analyzed through descriptive analysis. The results for each section were analyzed using the statistics provided by Qualtrics for each specific question. Once the data was organized it was entered into the SPSS software. The data was cleaned and all variables were renamed to match the research codebook and
Once on SPSS, specific variables were either recoded or computed to provide specific scores. Descriptive statistics using frequencies with skewness and kurtosis and cross-‐tabulations with correlations were conducted multiple times for the following categories: diagnosis of a gluten-‐ free diet, knowledge, perception, sources of information, purchasing and dieting behaviors and adherence.
• To identify individuals who self-‐diagnosed themselves versus those who are medically diagnosed with either Celiac Disease, Gluten Sensitivity or Irritable Bowel Syndrome answers to the fourth question of the questionnaire, what best describes why you follow a gluten-‐free diet (Q4) were recoded into two groups: medical diagnosis and self-‐
criteria: Celiac Disease, Gluten Sensitivity and Irritable Bowel Syndrome. The statistical analyses used for this category were frequencies and cross-‐tabulations (Table 2).
• Reasons why consumers choose to follow a gluten-‐free diet were identified through the question why do you follow a gluten-‐free diet (Q7). Answer choices in this question were categorized into two groups: medical versus social reasons and were analyzed using bivariate correlation analysis (Table 3).
• Total Knowledge score was achieved by creating a scale for questions eleven and twelve of the survey, which asked the participants to identify products and ingredients that contain gluten. Scores were calculated based on the number of products that the
respondents got correct. The score for these two questions was added to question nine, which asked the participants to correctly identify the definition of gluten.
Question eleven score: 16 + Question twelve score: 26 + Question nine score: 1
Total Score: 43 (100%)
The total score was computed out of forty-‐three points. Participants who correctly answered all three questions obtained a score of 100%. The mean scores for total knowledge were calculated using an independent-‐samples t-‐test and a Mann-‐Whitney U test for statistical significance reinforcement (Table 4).
• Perception of wheat and gluten was measured through a 5-‐point Likert scale, which asked participants to indicate their level of agreement or disagreement with the following statements: wheat is good; gluten is good. The mean and standard deviation for these categories were obtained through frequencies and cross-‐tabulations (Table 5).
• Sources of Information utilized by participants to acquire information regarding gluten were identified through the question where do you get your information about gluten. Answer choices in this question were categorized into two groups: medical versus social sources and were examined using bivariate correlation analysis (Table 6).
• Purchasing behaviors of consumers was identified through the question what prompts you to buy gluten-‐free products. Answers to this question were divided into three categories: food allergy, health and nutrition and “other”. The mean and standard deviation were obtained by running frequencies and cross-‐tabulations (Table 7).
• Important features of the food label were compared between the medical diagnosing and self-‐diagnosis group using a univariate/two-‐way between groups analysis of
variance (ANOVA). The mean and standard deviation is illustrated in Table 8, and the full table is displayed in Appendix C.
• Dietary Behaviors of consumers were measured by first looking at the dieting history of the participants, which was scored based on answers to the questions do you follow a special diet and have you ever tried any of the following diets.
! A score of zero meant that the participants have never followed a special diet. ! A score of 1 meant that participants have followed one diet in their lifetime. ! A score of 2-‐4 meant that participants have tried several diets throughout their
Dieting history means were compared using an independent-‐samples t-‐test and a Mann-‐ Whitney U test for statistical significance reinforcement (Table 9).
• Another set of questions aimed at consumers’ strategies for using alternatives to gluten-‐ containing foods were asked to measure dietary changes of participants. The answer options for these questions included: any item labeled gluten-‐free, only specific gluten-‐ free brand names, other grains such as corn and rice, meat products, dairy products or fruits and vegetables. Answers to these questions were compared to individuals who were diagnosed by a medical doctor and those who self-‐diagnosed. Mean and standard deviation were obtained through frequencies and cross-‐tabulations (Table 10).
• Nutritional consequences of a gluten-‐free diet were assessed through the question How have the following food groups changed in your diet since starting a gluten-‐free diet? (Q27). An independent-‐samples t-‐test was utilized to compare the means of each
category and a Mann-‐Whitney U was used to reinforce any statistical significance finding (Table 11).
• Total adherence to a gluten-‐free diet was computed by combining the scores of the following four questions:
! Question 16: How often do you buy gluten-‐free products?
! Question 17: When I do buy one of the following products, I buy the gluten-‐free version:
! Question 19: Have you had difficulty accepting a gluten-‐free diet? ! Question 22: Do you ALWAYS follow a gluten-‐free diet?
Question sixteen answer = “Always”: 1 + Question seventeen answer = “Yes to all”: 9 + Question nineteen answer = “No, not at all”: 1 + Question twenty-‐two answer = “yes”: 1
Total Score: 12 (100)%
Total adherence score was calculated out of twelve points. Participants who earned all twelve points received a score of 100%. The mean scores were compared using an independent-‐samples t-‐test and Mann Whitney U test was utilized to reinforce statistical significance (Table 12).
Adherence to a gluten-‐free diet was furthered analyzed through a one-‐way analysis of variance (ANOVA) to identify statistical significance within the three main medical
diagnosis categories (CD, GS, IBS). A Post Hoc test was used to identify the statistical significance between Celiac Disease and Irritable Bowel Syndrome (Table 13).
Further, quality of life, which is often an indicator of adherence, was scored based on three questions.
! Question 19: Have you had difficulty accepting a gluten-‐free diet?
! Question 24: Do you feel embarrassed about asking for gluten-‐free foods when you are out?
! Question: 25: Have you given up any group activities because you are afraid you might be tempted not to follow a gluten-‐free diet?
Question nineteen answer “Yes”: 1 Question twenty-‐four answer “yes”: 1 Question twenty-‐five answer “yes” :1
Total Score: 3 (100%)
The total score for quality of life had an inverse relationship meaning: ! Score 0 = Excellent quality of life
! Score 1 = Good quality of life ! Score 2 = Average quality of life ! Score 3 = Poor quality of life
Mean and standard deviation for this category was obtained using frequencies and cross-‐tabulation (Table 12).
Two hundred and forty-‐nine responses were collected. Thirty-‐one respondents did not
complete the survey and their responses were excluded from the statistical analysis resulting in an 87.5% questionnaire completion rate. The remaining two hundred and eighteen responses were entered into SPSS for analysis; however, of all the participants who did complete the survey only respondents who identified as having followed a gluten-‐free diet (n=73) were utilized for a full analysis.