## 4 Experiment and Result Analysis
### Subjects and Dataset  
The experimental dataset is taken from the Korea National Health and Nutrition Examination Survey (KNHANES), which is conducted by the Korea Centers for Disease Control and Prevention (KCDC). The KNHANES dataset contains a health examination for various numbers of diseases, health interview, and nutrition surveys. In this way, some considerable necessary features were surveyed from a minor of the population with around only one year. Therefore, the dataset contains features that have a large number of missing values and outliers. We have analyzed the dataset collected from 2009 to 2017 among the Korean population, after acquiring permission from the KCDC ([[http://knhanes.cdc.go.kr](http://knhanes.cdc.go.kr)]([http://knhanes.cdc.go.kr](http://knhanes.cdc.go.kr))). Regarding the classification target, it needs to generate the target population for eliminating irrelevant features and instances. Additionally, only adults aged 18 years or older who were considered for smoking-related surveys. Current and former smokers were defined as those who have smoked at least 100 cigarettes in their life. On the contrary, individuals who have never smoked or have smoked less than 100 cigarettes in their life were considered as non-smokers. Initially, the total number of subjects was 75,292, constituting the total number of the collected data. Similar to the literature [22; 23; 31], we selected 22 features. Subjects were eliminated from the current study based on the following exclusion criteria:  
* We excluded 53,850 subjects who never smoked. * We excluded 9271 subjects who never tried to quit smoking cigarettes in their life by smoking cessation methods. The smoking cessation methods of the KNHANES dataset consist of interventions such as smoking quit agent, smoking quit clinic of the public health center, doctor prescribed medication, and no smoking guides by telephone, internet and various kind of counseling, which were used to determine class labels. Then, 8479 subjects were excluded due to missing value and outliers, which were stored in given initial features. The outliers and extreme values were removed based on the interquartile range. The exclusion process of missing value and outlier produced the 3692 subjects with 22 features. According to the classification target, we use the \"smoking status of adult\" feature that has three groups such as smoking\", \"sometimes smoking\" and \"quit smoking\". In this study, \"smoking\" and \"sometimes smoking\" are considered as unsuccessful smoking quitters, whereas \"quit smoking\" is defined as a successful quitter, which means a person who used to smoke but had not smoked in the past 1 year. Descriptive characteristics of the former and current smokers are provided in Table 2. Consequently, 951 (25.7%) of the smokers can quit smoking habit successfully after attending at least one smoking cessation intervention voluntarily. This target class is recognized by imbalanced distribution. In comparison to socio-demographic features, we found evidence that approximately 90% of subjects were men among former and current smokers. Men were more likely to smoke than women; thus, 856 (25.9%) of men and 95 (24.4%) of women were resulted by successfully smoking quitters in our study. For the age group, (<35 years) subjects were less likely to quit smoking than other age groups. Taken together, 14.09% of <35 years, 21.90% of 36-45 years, 26.30% of 46-55 years and 40.89% of >56 years had successfully quit smoking. Among the body mass index, lower weights (13.0-19.0) of subjects were markedly less likely to quit smoking by about 7% than other groups. Among the smoking cessation rates by the urban and rural population, urban areas had two times higher successful quit rates than rural. Therefore, the subjects starting smoking in age groups 27.01% of <18 years, 23.40% of 19-24 years and 28.05% of >25 years were estimated to quit smoking, respectively. Thus, subjects who started to smoke in the age group of 19-24 years are less likely to quit smoking than other age groups.