Happiness is defined as experiencing positive emotions more frequently and negative feelings less frequently of an individual and being highly satisfied from life (1,2). Happiness is consequence of cognitive and sensory evaluation about life of individual according to this definition. Frequency of experiencing positive and negative emotions make up sensory aspect of happiness and evaluations about life make up cognitive aspect of happiness in this definition (2,3). Experiencing positive emotions such as trust, joy, delight and hope frequently and experiencing negative emotions such as anger, hatred, anxiety, fear, hopelessness and sadness and being satisfied (to be happy with) from life domains such as marriage, work or health in general are accepted as indicators of happiness (4).
Research about positive psychology and happiness in particular has substantially been increased since 1980’s. Various assessment tools have also been developed to assess happiness by increasing research on happiness. One of the most frequently utilized assessment tools in these studies is Oxford Happiness Inventory (OHI) developed by Argyle et al. (1). OHI is an assessment tool prepared in Beck Depression Inventory format (5) and consisted of 29 sets and four different items at each set. The scale represents good psychometric characteristics with this format; however, due to long duration of administration, it was revised by Hills and Argyle (6) and converted to a Likert-type assessment tool with 29 items.
There is increasing interest on research about positive psychology and happiness both in Turkey and the world. Research about happiness has substantially increased particularly since 2000 (4,7-10). For this reason, adaptation of scales about happiness having international validity and reliability will be beneficial for future research. In our study, we aimed to investigate psychometric characteristics of Turkish form of Oxford Happiness Questionnaire. The scale is thought to fill an important gap in studies about happiness in Turkey. Moreover, this assessment tool which is widely used in other cultures will make it easier to evaluate the situation of Turkish society at intercultural studies about happiness. In this context, psychometric properties of OHQ were examined by paraphrasing and confirmatory factor analysis, inner consistency and criteria-related validity methods and hypothesis of having similar psychometric properties with original form was tested.
Four hundred and ninety-one (334 women/154 men) university students who were being educated at Sakarya University School of Education at 2011-2012 term are participants of this study. Three participants did not declare their gender. Ages of participants were 17-37 and mean was 19.50 (SD=2.23). All participants were administered Oxford Happiness Inventory (OHI) and randomly selected 173 participants were also administered other scales described in data collection tools section alongside with OHI.
Data Collection Tools
Oxford Happiness Questionnaire (OHQ): OHQ is an assessment tool developed by Hills and Argyle (6) to assess happiness having 29 items in 6-item Likert-type (1-Not agree, 6-Fully agree). Hills and Argyle (6) reported inner consistency coefficient (Cronbach alpha) of the scale as 0.91. After factor analysis to determine structural validity of the scale, an 8-factorial structure having self-value over 1 was obtained. However, due to problems in interpreting and naming of these factors, it was concluded that it will be better to utilize the scale with a single factor. Relationship between Life Satisfaction Scale (11), Depression-Happiness Scale (12), Life Orientation Test (13), Rosenberg Self-Esteem Scale (14), Life Interest Scale (15) and Eysenck Personality Questionnaire (16) with OHQ were also examined in this study. According to this, a correlation between OHQ and these scale was found at p<0.001 significance level and correlation of r=0.77, r=0.90, r=0.79, r=0.81 and r=0.77, consecutively. Among sub-scales of Eysenck Personality Questionnaire, correlations between OHQ and “extraversion” (r=0.61, p<0.001), “neuroticism” (r=-0.59, p<0.001) and “psychoticism” (r=-0.17, p<0.05) were found. A correlation of 0.80 (p<0.001) was also found between OHQ and original form of the scale (Oxford Happiness Inventory).
Life Satisfaction Scale (LSS): This scale was developed by Diener et al. (11). Scale consisted of 5 items and has 7-item Likert-type answer key. Score can be achieved from scale is between 5 and 35. Higher scores indicate higher satisfaction from life. Diener et al. (11) reported inner consistency of the scale as 0.87 and test-retest reliability coefficient as 0.82. Turkish adaptation of the scale was done by Yetim (17). Yetim (17) reported test-retest reliability coefficient as 0.85 and inner consistency as 0.76. Reliability coefficient of LSS was found 0.86 in this study.
Life Orientation Test (LOT): This scale was developed by Scheier and Carver (13) to assess optimism and consists of 12 items (four items as filling items). LOT is a self-rating scale in 5-item Likert-type (1-Not agree, 5-Fully agree). When items coded in reverse are converted, higher scores achieved from scale indicate a higher optimism. Turkish adaptation of LOT was done by Aydın and Tezer (18). According to this, inner consistency of scale was found 0.72 and test-retest reliability coefficient was found 0.77 as a result of administering after four weeks (18). Inner consistency coefficient of LOT was found 0.79 in this study.
Positive Affect Negative Affect Scale (PANAS): This scale was developed by Watson, Tellegen and Clark (19). Scale consisted of 20 affective expressions, 10 of which are positive, and 10 of which are negative. It has 5-item Likert-type answer sheet (1-Not appropriate, 5-Fully appropriate). Watson et al. (19) reported inner consistency of the scale as 0.86-0.90 for “positive emotions” dimension and 0.84-0.87 for “negative emotions” dimension. Turkish adaptation of the scale was done by Gençöz (20). Gençöz (20) determined reliability coefficients (Cronbach alpha) of the scale as 0.83 for “positive emotions” sub-dimension and 0.86 for “negative emotions” sub-dimension. In this study, reliability coefficients for “positive emotions” and “negative emotions” sub-dimensions were found as 0.85 and 0.84, consecutively.
Subjective Happiness Scale (SHS): This scale was developed by Lyubomirsky and Lepper (21). SHS is a 7-item Likert-type self-rating tool. Scale consisted of 4 items. Lyubomirsky and Lepper (21) reported inner consistency of the scale between 0.79 and 0.94 at different samples. Test-retest reliability was found between 0.55 and 0.90. Turkish adaptation of scale was realized by Doğan and Totan (22). According to this, inner consistency coefficients were found to be between 0.65 and 0.70 at different samples. After confirmatory factor analysis done to determine factorial structure of scale, it was concluded that single factorial structure was preserved like it is in original form (CFI= 0.93, NFI= 0.92, IFI= 0.93; GFI= 0.96). Inner consistency coefficient of SHS was found to be 0.67 in this study (22).
Adaptation studies of the scale were started by linguistic validity. For this process, scale was translated from its original English version to Turkish by five independent people who are experts of both languages. Items which were thought to represent each item were included in the Turkish version after examining all translated texts. This Turkish version was subsequently reverse-translated to English by an academic from psychological counseling field. Translated text was compared to original version, required corrections were done and Turkish version was finalized. After obtaining linguistic equivalence of scale, implementation was initiated. Scale was administered at class hours and volunteered students were required to attend the study after necessary information was given. Administration was realized without time constraint and continued approximately 15-30 minutes. Descriptive and confirmatory factor analyses, inner consistency and criteria-related validity methods were used in data analyses. Data analysis was realized by SPSS 15 and Lisrel 8.7 software.
Mean score achieved from scale was found 0.119 (SD=20.13) for the whole sample and score range was 53-168. Higher scores indicate higher level of happiness. When happiness scores were evaluated regarding gender, mean score for men was found 120.87 (SD=18.58) and for women 118.98 (SD=20.81). Correlation between happiness scores and gender was examined by independent samples t test and no statistical difference was found (t=0.96, p=0.34). Obtained values were presented at Table 1.
Descriptive Factor Analysis (DFA): Kaiser-Meyer-Olkin (KMO) and Barlet Sphericity tests were performed to understand whether data set is suitable for factor analysis. For suitability of data for factor analysis, Kaiser-Meyer-Olkin (KMO) should be over 0.60 and Barlett Test should be statistically significant (23). KMO sample suitability coefficient was found 0.92 and Barlett Sphericity Test χ2 value 5032.35 (p<0.001). These results indicated that our data were suitable for factor analysis. After analysis performed by basic components analysis and without any rotation, a 7 factorial structure having core value over 1 was obtained. However, it was observed that scale items were collected at first factor and first factor substantially contributed to variance. Due to small contribution of other six components to variance and not being able to be named, analysis was repeated after limiting with single factor as it is in its original version. After the analysis, due to 0.13 factor load of item 5 (I rarely wake up rested in mornings), item was excluded from scale and analyses were repeated. According to this analysis, a structure with core value of 8.3 and explaining 29.84% of total variance was obtained. Factor loads of scale varied between 0.32 and 0.77 (Table 2).
Confirmatory Factor Analysis (CFA): CFA was performed by using Maximum Likelihood Estimation Method to determine whether single factorial structure of Oxford Happiness Questionnaire can be confirmed in a sample consisting of Turkish university students. For this purpose, “critical N value” (Critical N-CN) was first examined to evaluate adequacy of study sample. CN value for CFA was found 163.12. This value indicates that sample of 491 units forming the study group is adequate for confirmatory factor analysis in our study.
There are many goodness-of-fit indices to evaluate suitability of model according to CFA results. Several goodness-of-fit index values are recommended to be utilized to perform suitability of the model due to strong and weak aspects of suitability indices in differentiating theoretical model and real data (24). Suitability of the model was first assessed by proportion of chi-square values over freedom degree in this study. Value less than 3 indicates goodness-of-fit and value less than 5 indicates acceptable fit. Values over 0.95 for Comparative Fit Index (CFI), Incremental Fit Index (IFI), Relative Fit Index (RFI), Normed Fit Index (NFI), Non-Normed Fit Index (NNFI) indicate goodness-of-fit and values between 0.90 and 0.94 indicate acceptable fit. Values for Root Mean Square Error of Approximation (RMSEA) and Standardised Root Mean Square Residual (SRMR) less than 0.05 indicate goodness-of-fit and values between 0.06 and 0.08 indicate acceptable fit (25-28). It can be said that single factorial structure of the scale is preserved in this sample of Turkish university students according to these criteria. Standardized loads, t-value and R2 values regarding DFA are presented in Table 3 and goodness-of-fit index values are presented in Table 4.
Relationship between Oxford Happiness Questionnaire (OHQ) and, Subjective Happiness Scale (SHS), Life Orientation Test (Optimism Scale), Positive-Negative Affect Schedule (PANAS) and Life Satisfaction Test (LST) were examined for criteria-related validity. Significant correlations between OHQ and other assessment tools evaluating happiness and optimism were found according to analyses (Table 5). These results indicate that OHQ has a good level of goodness-of-fit.
Reliability of OHQ was examined by composite reliability, inner consistency and test halving methods. According to this analysis, inner consistency coefficient of the scale was found 0.91 and reliability coefficient obtained by test halving method was found 0.86. Reliability coefficients 0.70 and over obtained by inner consistency and test halving methods are accepted as adequate in the literature (23). Composite reliability was found 0.91. Composite reliability is calculated by factor loads and error ratios after confirmatory factor analysis. Acceptable value for Composite reliability was reported 0.70 and over (25). These results indicate that scale has high level of reliability values.
In this study, we aimed to examine validity and reliability of Oxford Happiness Questionnaire (OHQ) developed by Hills and Argyle (6) in a sample of Turkish university students. For this purpose, validity of OHQ was tested by descriptive and confirmatory factor analysis methods; reliability was tested by inner consistency, test halving and composite reliability methods. Our findings indicate that Turkish version of OHQ has similar psychometric properties with its original version.
After descriptive factor analysis done to determine factorial structure of the scale, a single factorial structure was obtained as it is in the original version. Fifth item of the scale (I rarely wake up rested in mornings) was excluded due to low factor load. Confirmatory factor analysis was performed to determine confirmation of single factorial structure in a sample consisting of Turkish university students. It was concluded that single factorial structure is preserved by CFA. At criteria-related validity, validity and reliability of OHQ was proved and its correlation between other assessment tools evaluating happiness and optimism was examined. Results of the analysis indicated that there are statistically significant and substantial correlations between subjective happiness, life satisfaction, optimism, positive and negative emotions. These results may be evaluated as a proof of validity of OHQ. Reliability of OHQ was examined by composite reliability, inner consistency and test halving methods. Finally, total OHQ scores were analyzed according to gender and being a man or woman was found not to be correlated with happiness levels of university students.
Our study has some limitations. First of all, it was performed in a sample consisting of only university students. It will be appropriate to examine psychometric properties of the scale in samples who are not students. In this study, reliability of the scale was examined by composite reliability, inner consistency and test halving methods. Determining reliability of the scale can be suggested by test-retest method in future studies. Fifth item of the scale was excluded due to low factor load and total item correlation. There was an agreement that this item could not be fully understood by participants due to its negative content. In future studies on the scale, this item can be converted to a positive expression and thus included in the scale.
Five important conclusions were achieved according to this study results:
1) Turkish version of Oxford Happiness Questionnaire (OHQ) has a single factorial structure.
2) Turkish version of OHQ has a high level of reliability.
3) There is a significant correlation between Turkish version of OHQ and other assessment tools assessing happiness.
4) No differences regarding gender were found in total scores of Turkish version of OHQ.
5) Turkish version of OHQ can be utilized as a valid and reliable assessment tool to evaluate happiness in university students.
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