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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 11  |  Issue : 1  |  Page : 141

Developing and validating food choice determinants questionnaire: An instrument for exploring food choice determinants in Iran


1 Department of Community Nutrition, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
2 Department of Anthropology, Faculty of Social Sciences, University of Tehran, Tehran, Iran; Department of Population Health Sciences, University of Bristol, Bristol, UK
3 Research Center for Social Determinants of Health, Research Institute of Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran

Date of Submission08-Jul-2019
Date of Acceptance14-Oct-2019
Date of Web Publication05-Sep-2020

Correspondence Address:
Naser Kalantari
No. 7, Hafezi (West Arghavan) St., Farahzadi Blvd., Qods Town, Zip Code: 1981619573, P.O.Box: 19395 – 4741, Tehran
Iran
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijpvm.IJPVM_250_19

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  Abstract 


Background: This study was carried out to design and validate a questionnaire to measure the majority of factors influencing food choices among adults in Iran. Methods: A sequential exploratory mixed-method approach was applied to develop the initial item pool of the Food Choice Determinants Questionnaire (FCDQ) starting with a qualitative study to explore the food choice dimensions and its components. Designing the initial questionnaire using these dimensions and the 36-item Food Choice Questionnaire (FCQ) was then performed. The face, content, and construct validity were also assessed. The construct validity of the questionnaire was assessed using the exploratory factor analysis (EFA). Cronbach's alpha was applied for each main theme to examine the internal consistency. Results: After content and face validity process, a 60-item FCDQ was developed with total items' content validity index (CVI) of 0.69 indicating a reasonable level. The Cronbach's alpha coefficients for each of the six constructs in the scale have shown satisfactory internal consistency. Conclusions: This instrument is valid and reliable to measure food choice determinants in adults and could be applied to design interventions aiming to better food choice.

Keywords: Choice behavior, decision-making, determinants, food, Iran, surveys and questionnaire


How to cite this article:
Roudsari AH, Vedadhir A, Amiri P, Kalantari N, Omidvar N, Eini-Zinab H. Developing and validating food choice determinants questionnaire: An instrument for exploring food choice determinants in Iran. Int J Prev Med 2020;11:141

How to cite this URL:
Roudsari AH, Vedadhir A, Amiri P, Kalantari N, Omidvar N, Eini-Zinab H. Developing and validating food choice determinants questionnaire: An instrument for exploring food choice determinants in Iran. Int J Prev Med [serial online] 2020 [cited 2020 Sep 22];11:141. Available from: http://www.ijpvmjournal.net/text.asp?2020/11/1/141/294404




  Introduction Top


There is enough evidence that unhealthy diet is a strong predictor for non-communicable diseases (NCDs) including obesity, cardiovascular diseases, some diet-related cancers, diabetes, and other disorders that, overall, are called civilization diseases.[1] NCDs are recognized as the prominent health issues, which have led to 236,000 deaths in Iran, and dietary elements were recognized as the main risk factor for NCDs.[2]

Food choice is a multifaceted process that is dependent on numerous factors with impacts on individual behaviors through many pathways leading to selection or rejection of foods. These factors vary from sensory, physiological, and psychological responses of consumers to interfaces between social, environmental, and economic effects, containing the variety of foods and food industry actions to endorse them.[3],[4] It is needed to provide a valid, reliable, and culturally tailored instrument for discovering the multiple aspects of food choice. To date, many research have been conducted on food choice motives around the world, of which many of them have examined the items of Steptoe's questionnaire in the areas studied with the aim of determining the proportion of these items in factors influencing food choices.[5],[6],[7],[8],[9],[10],[11],[12] This Food Choice Questionnaire (FCQ) as a tool that is developed in Western culture does not seem to capture many cultural background and characteristics that are specific to the Middle Eastern societies. In addition, this instrument was developed in 1995 based on the social context of that period of time and may not cover all possible aspects of food choice in today's world. Hence, this study aimed to address thought, meanings, feelings, views, habits, and cultural aspects of food choice in Iranian people, as a sample of Middle Eastern societies using a qualitative study.


  Methods Top


Ethical considerations

Ethical issues (including plagiarism, informed consent, misconduct, data fabrication and/or falsification, double publication and/or submission, redundancy, etc.) have been completely observed by the authors.

Study design

This study used an exploratory sequential mixed-method research design. This approach is applied to design and validate the research instrument and usually begins with a qualitative initial phase and is followed by a quantitative phase; the results of both phases are then used in the interpretative analysis.[13],[14] Details of the whole procedure are as follows.

Phase 1: Identifying dimensions of the food choice determinants

Qualitative study: Because the purpose of this study was to explore the process of choosing foods in Iranian adults, a qualitative study using an in-depth interview technique with the grounded theory methodology was applied to construct a theory based on systematic data gathering and analysis inductively.[15] The participants were chosen with maximum diversity with regard to occupation, education, and socioeconomic status in Tehran, capital of Iran. The interviews were conducted using an interview protocol based on Strauss and Corbin protocol.[15] Each interview lasted between 25 and 40 min and was recorded completely, and then the key points were noted. Purposive sampling was replaced with theoretical sampling to complete the created theory and continued until the theoretical saturation. Data were managed and coded using MAXQDA 10 software.

Phase 2: Development and validation of the instrument

  1. Item generation: Inductive–deductive approach was used to construct the questionnaire items. In the inductive approach, items were generated using the main concepts explored through the qualitative research using important open codes that shaped the main concepts, and in the deductive approach, we profited the 36-item FCQ designed by Steptoe et al.[16] as well as the “food choice process model” developed by the research group of food choice at the Cornell University using the qualitative research for American adults[17],[18]


  2. A Likert-type scale was used with five options from “completely agreed” to “completely disagreed” for attitude-related items and “always” to “never” for practice-related items.

  3. Content validity: Content validity of the constructed questionnaire was evaluated through two approaches: expert panel opinion (the qualitative method) and content validity index (CVI) and content validity ratio (CVR) calculation (the quantitative method).[19] The expert panel consisted of 10 experts (5 nutritionists and 5 sociologists) who assessed the initial questionnaire qualitatively in terms of “compliance with grammar,” “content representativeness,” “wording,” and “item allocation,” and then, item modification was carried out before the quantitative content validity


  4. In the quantitative phase, content validity was numerically calculated using two indicators: CVI and CVR. The CVI was used to evaluate items for “simplicity,” “relevancy,” and “clarity,” while the CVR was applied to assess “necessity” of each item. If the CVI score was less than 0.7, the item would be omitted.[20] Considering the number of the expert team members (12 persons), the acceptable CVR was above 0.56 based on the Lawshe “minimum CVR value” table.[21]

  5. Face validity: Face validity of the questionnaire was determined by the qualitative and quantitative methods. A total of 15 adults age 30–64 years old were selected through convenience sampling and 22 experts were recruited selectively to evaluate face validity of the items in terms of “difficulty,” “irrelevance,” and “ambiguity.” After the content and face validity phase, the questionnaire was modified
  6. Construct validity: To determine the exact sample size for construct validity study, a pilot study was conducted on 70 volunteers age 30–64 years old living in Tehran. Based on the results of the pilot study, necessary modifications were made to the items and the sample size for construct validity study was determined. The sample size was estimated at 680 that increased to 750 taking into account the drop-outs. Multistage cluster sampling was used in Tehran with five geographical clusters of north, south, east, west, and center based on the probability proportional to size (PPS) sampling. Then, some cultural, religious, health, and therapeutic centers as well as sport clubs and grand parks were randomly selected in each area


  7. Exploratory factor analysis (EFA):Principal axis factoring (PAF) to extract the factors and Promax rotation with Kaiser normalization were used to explore the existing factorial pattern. The criteria used to explore the main factors were as follows: value of extraction, initial eigenvalues, rotated component matrix, percent of variance explained by each factor, and Kaiser–Meyer–Olkin (KMO) measure of sampling adequacy. Decision on the number of factors and deleting items due to item's factor loading were made by the research team.[22]

  8. Reliability: To examine the internal consistency of the themes (scales) of the tool, Cronbach's alpha was applied for each main theme.


Statistical analysis

At first, the normality test was conducted to check the distribution of data using the Kolmogorov–Smirnov test. Cronbach's alpha was used to evaluate the internal consistency, and values equal to 0.7 and above were acceptable.[23] The EFA was used to explore the main themes and load the items into groups. The internal consistency coefficient was evaluated using the Bartlett's and KMO tests. Consequently, the factor pattern matrix was used using Promax rotation. The factors were chosen if their eigenvalue was more than 1 and the items with the loading factor of more than 0.5 remained in the questionnaire.[24]


  Results Top


Phase 1: Identifying dimensions of the food choice process

Qualitative study: Theoretical saturation was attained after 33 interviews with adults age 20–64 years old. The transcripts were reviewed, and subsequently, open codes were extracted and combined in the constant comparative analysis into the conceptual concepts and themes using Strauss and Corbin style of coding[15] as presented in [Table 1].
Table 1: Main constructs and themes extracted from the qualitative study (Phase 1)

Click here to view


Phase 2: Development and validation of the instrument

  1. Item generation: Based on the concepts derived from the qualitative study, 260 items remained after elimination of repetitive codes. After final assessment of the item pool by the research team in terms of concordance between the items and related concepts and eliminating redundant items, the total number of items was reduced to 179 Likert-type items
  2. Content validity: Based on the numerical CVR, there were 103 items with CVRs lower than 0.56. Final decision on deletion or nondeletion of the items was made by examining the item impact method (quantitative face validity). As a result, 89 of the 179 items had the item impact method of more than 1.5, meaning that they were recognized as important by adults age 30–64 years old. Items with lower scores in both the CVR and item impact method were excluded from the study. For items that were low in one of the two indices, decisions were made based on the importance of issues and research objectives. Finally, content validity process resulted in elimination of 67 items and a modified questionnaire with 112 items
  3. Face validity: Each participant's opinion(s) about the importance of the existing items in the questionnaire as factors affecting the process of choosing food and their feedback about the item meaning and their simplicity were used to improve clarity and comprehensibility of the items
  4. Construct validity: The mean age of 70 adults whoparticipated in the pilot study was 42.3 years (standard deviation, 10.2); moreover, the percentage of employed people and homemakers was 44.3 and 24.3, respectively. The majority of the participants (77.1%) were married and 70.1% of them had children. Cronbach's alpha for items in each construct of the questionnaire was above 0.7 indicating suitable interrelatedness among the items. Thus, the questionnaire was identified appropriate to carry out the main construct study. Ultimately, 722 questionnaires were completed (the valid response rate: 96.2%), and their demographic characteristics are shown in [Table 2]
  5. Table 2: Demographic details of the adults who participated in the construct validity study (n=722)

    Click here to view


    EFA: The results of EFA are shown in [Table 3]. Regarding the sociocultural determinant construct in the Food Choice Determinants Questionnaire (FCDQ), due to the widespread concept of this construct, factor analysis was carried out independently for each theme.
    Table 3: Factor analysis results and item statistics of food choice dimensions in the adults (n=722)

    Click here to view


  6. Reliability: The Cronbach's alpha coefficients for each of the six constructs are presented in [Table 3].



  Discussion Top


This study was the first effort to design and assess an instrument for measuring the process of food choice among adults in the sociocultural context of Iran. All the aspects and characteristics of the process of choosing food were designed according to the participants' quotes in the qualitative study and then studied in the form of items in this questionnaire. FCDQ was designed based on the social and cultural backgrounds of the Iranian society. All the psychometric phases of the instrument development including face, content, and construct validity were completely undertaken for the questionnaire. EFA was used to evaluate construct validity of the tool. Considering that the constructs obtained from the qualitative study were conceptually separate from each other, the EFA was performed by the principal component analysis using Promax rotation for the six constructs separately. After performing the validity and reliability steps, the FCQ comprised 60 items within six areas as shown in [Table 3]. Because the questionnaire was designed using the grounded theory methodology and validated in Tehran's adult society for the first time, it is a valid and reliable questionnaire to examine the determinants of food choices.

The findings of the existing studies revealed that the food choice process has many aspects such as social, cultural, economic, and individual aspects. Moreover, as observed in the literature, there also exist other aspects in relation to food choice that should be deliberated as a latent and complex concept with multiple dimensions that suggest the necessity of a multidimensional tool.[25] The only quantitative tool in the field of food choice in its general sense is the questionnaire designed by Steptoe et al. that has been designed over the past 20 years and developed in a different social and cultural context than the Iranian society.[16] This tool consisted of nine concepts: health, moods, convenience, sensory appeals, and natural content of food, price, weight control, familiarity, and ethical considerations. Our newly developed questionnaire contained the mentioned concepts, as well as some additional concepts, for example, organic food choice, cost-effectiveness, and agency in choice, climate condition, and seasonal consideration. The factors recognized with the factor analysis in the 60 items in this research questionnaire included organic selection, quality, cost-effectiveness, health, diversity, agency, habitus and life experiences, seasonal climatic conditions, understanding the role of traditional foods, inspiration from traditional medicine, social relations, occupational constraints, knowledge promotion, family structure, turning points in changing food habits, trajectories in food patterns, provision of children's need and satisfaction, economic feasibility, and food health indicators. Many of these new concepts or themes were derived from the changes taken place in people's lifestyle in recent years.

Individual food systems are mental processes in which people influence food choices on how and what to eat in certain conditions.[17],[26] As the “individual habitus and characters” theme was loaded with one factor including four items, it led to lower internal consistency values (equal to 0.63); however, this value was close to 0.7.[24] The lower reliability detected for the construct “environmental and ecological characteristics” consisted of two items which resulted in lower reliability (equal to 0.21). Due to the distinct subthemes of the construct “sociocultural determinants,” its overall value for the construct was lower than 0.7 (equal to 0.54); however, the lower value of reliability will not certainly deny the importance of this construct. In addition, the sociocultural items of the tool were valuable from the point of view of the expert panel and research team.

The FCDQ was developed and validated using mixed-method design which permits to explore participants' views deeply. In addition, this study was conducted in the adult age group which is now a large population in Iranian society. As previously pointed out, because the items of the questionnaire were developed based on the participants' statements and experiences, they are most closely associated with the mentality of the population in the community.


  Conclusions Top


The FCDQ is a valid and reliable tool to evaluate the determinants of food choice in adults and can be used to assess the main determinants of food choice for future researches and accessible to conduct similar study design in a different setting and sociocultural context.

Declaration of participants consent

The authors certify that they have obtained all appropriate consent forms. The participants understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgments

The authors appreciate all the participants who took part in this research project and the Research Deputy of National Nutrition and Food Technology Research Institute (NNFTRI).

Financial support and sponsorship

This project was supported by National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences.

Conflicts of interest

There are no conflicts of interest.





 
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