3.1. Design and Sample
This was a cross-sectional study approved by Research Council and Ethics Committee of Mazandaran University of Medical Sciences, Sari, Iran (Ethics Code:1498.Code: IR.MAZUMS.REC.94.1498) on 118 couples referring to healthcare settings from March to September 2015 in Sari, Iran. The inclusion criteria to recruit the sample were a willingness to take part in this study, Iranian nationality, women at the reproductive age (15 - 44 years old), and living with the spouse for at least one year at the time of data collection (
30). Using a multistage random sampling method, the sample size was determined as 118 people. A previous study on the determination of sexual differences in the different domains of intimacy among married university students in Tehran in 2008 reported the standard deviations of marital intimacy in married women and men as 60.46 and 51.35, respectively (
27). Given the average standard deviation of marital intimacy reported by the above-mentioned study (SD = 55), 95% confidence interval, and the power of 90, the sample size was determined as 118 couples using the following formula:



To recruit the sample, the 20 urban healthcare centers were listed. In addition, according to the number of couples referring to each healthcare center in Sari, the healthcare centers were divided into two groups of with many clients and with a few clients. Next, given the proportion of the referrals to each group of healthcare centers, the quota of the first group (2/3 of the total sample) was estimated to be 77 couples and the quota of the second group (1/3 of the total sample) was 39 couples. Four centers were randomly chosen from each group of the healthcare centers and the required number of participants was recruited based on the proportion of couples referring to each healthcare center. It is noted that the table of random numbers was used to choose the participants. The heads of the households were contacted by phone. They were informed about the purpose and methods of this study and were asked to refer to the healthcare center with their spouses for data collection. At their referral, they were assessed using the inclusion criteria and written informed consent was taken from those who willingly agreed to participate in this study. They were assured that their rights, the volunteer nature of this study, and the confidentiality of data collection and analysis would be met. The questionnaires were distributed to 125 volunteer couples, and 118 couples filled out and returned the questionnaires for data analysis.
3.2. Data Collection
Data were collected using the socio-demographic questionnaire, the Bagarozzi’s marital intimacy needs questionnaire, Barton’s communication skills questionnaire, Hazan and Shaver’s adult attachment styles (1978) questionnaire, and the interpersonal conflict management style (ICMSI).
A thorough literature review by the authors showed that attachment styles, conflict resolution style, and communication skills could affect marital intimacy among couples. Since these variables could not be evaluated in couples just by asking simple questions, separate valid and reliable questionnaires were used for data collection.
Socio-demographic questionnaire: It included questions regarding age of the self, age of the spouse, the duration of marriage, educational level of the spouse, occupation, satisfaction with economic condition, health status, marital conflicts, duration of premarital relationship, marital satisfaction, and psychological, economic, sexual, physical, verbal, and overall violence.
The Bagarozzi’s marital intimacy needs questionnaire: It was designed by Bagarozzi (
4) to evaluate intimacy in emotional, psychological, logical, sexual, physical, spiritual, aesthetic, and social-recreational domains. The content validity of this questionnaire was confirmed by Etemadi et al. (
30) with 15 experts in the field of the study and 15 couples. To determine its reliability, this questionnaire was applied to 30 couples and the Cronbach’s alpha coefficient was reported as 0.94. The reliability of this questionnaire for each domain was assessed using a test-retest method, which showed the coefficients of 0.89 for emotional, 0.82 for psychological, 0.81 for logical, 0.91 for sexual, 0.80 for physical, 0.65 for spiritual, 0.76 for aesthetic, and 0.51 for social-recreational domains (
27). In the current study, the Cronbach’s alpha coefficient of this questionnaire was determined as 0.96. This questionnaire consisted of 41 questions classified into five questions for the evaluation of each domain of intimacy except for the spiritual domain that had six questions. It was rated on a 10-point scale from 1 (there is no such a need in me at all) to 10 (this need is strong in me). For the eight domains of intimacy, numerical scores were calculated and by summing up the scores of each domain, the total score of intimacy was calculated. The range of scores was from 41 to 410 (
31).
The Hazan and Shaver adult attachment styles questionnaire (1978): It was designed by Hazan and Shaver in 1978 comprising three descriptive paragraphs. The descriptive phrases were about the individual’s feelings of the comfortability and intimacy in relationships. If the participants chose the paragraph one as the best description for their feelings, they would be considered safe, and if they chose paragraphs two or three, they would be regarded as unsafe. Paragraph 2 showed the avoidant unsafe attachment style and paragraph 3 showed the anxiety unsafe attachment style (
32). The validity of this questionnaire was assessed using content validity, which meant that the content of its items was completely compatible with the structural concepts of the attachment theory. In addition, it was shown that its interactive extension was compatible with adults’ relationships. In a study, the reliability coefficient of this questionnaire using the test-retest method was found to be 0.82 (
33).
The Barton’s communication skill questionnaire (1990): it consisted of 18 items to evaluate the three domains of feedback skill, listening skill, and speaking skill with six questions in each domain. The content validity of the questionnaire was evaluated by a panel of experts and its reliability was confirmed by the Cronbach’s alpha coefficient of 0.7. A five-point Likert scale from completely disagree (score 1) to completely agree (score 5) was used to rate the questionnaire’s items. The minimum score in each domain was six and the maximum score was 30 (
34).
The interpersonal conflict management style (ICMSI): It had 28 questions with the purpose of evaluating the people’s styles of resolving conflicts with their spouses (
20). It consisted of five domains as the collaboration style (questions 1 - 7), the domination style (question 8 - 13), the adaptability style (questions 14 - 18), the avoiding style (questions 19 - 22), and compromise style (questions 23 - 28). This questionnaire was translated into Farsi in 2002 (
35). In a study, positive and negative correlations were reported between the subscales of the ROCI-II and the conflict resolution questionnaire (CRT), which showed the desired convergent and divergent validity for this questionnaire. The Cronbach’s alpha coefficients of the questionnaire’s subscales were reported in the range of 0.70 - 0.75. In the current study, the reliability coefficient of this questionnaire using the Cronbach’s alpha coefficient was reported as 0.81. The questionnaire’s response rating was based on a five-point Likert scale from completely disagree (score 1) to completely agree (score 5). The score of each domain as the summation of the scores of the items relevant to that domain indicated the score of that style of conflict resolution. The domain with a higher score showed that the respondent would use that style to resolve conflicts with the spouse. In addition, a higher score for the style indicated the respondent’s more intensive tendency toward that style (
36).
3.3. Data Analysis
Descriptive and inferential statistics were used to analyze data via SPSS v.18 software. Descriptive results were presented using the frequency, mean, and standard deviation. The inferential statistics were presented using ANOVA, t-test, Pearson correlation coefficient, paired-samples t test, chi-square, and multiple linear regression. Those variables with a statistically significant p value (< 0.05) entered into the multiple-linear regression model.