Analysis of an air quality data set

Air Pollution ◽  
2002 ◽  
pp. 334-349
Keyword(s):  
Air Quality ◽  
Quality Data ◽  
Data Set ◽  
Air Quality Data

scholarly journals Handling Complex Missing Data Using Random Forest Approach for an Air Quality Monitoring Dataset: A Case Study of Kuwait Environmental Data (2012 to 2018)

2021 ◽  
Vol 18 (3) ◽  
pp. 1333
Author(s):  
Ahmad R. Alsaber ◽  
Jiazhu Pan ◽  
Adeeba Al-Hurban 
Keyword(s):  
Air Quality ◽  
Missing Data ◽  
Random Forest ◽  
Missing Values ◽  
Imputation Method ◽  
Environmental Data ◽  
Environmental Research ◽  
Quality Data ◽  
Data Set ◽  
Air Quality Data

In environmental research, missing data are often a challenge for statistical modeling. This paper addressed some advanced techniques to deal with missing values in a data set measuring air quality using a multiple imputation (MI) approach. MCAR, MAR, and NMAR missing data techniques are applied to the data set. Five missing data levels are considered: 5%, 10%, 20%, 30%, and 40%. The imputation method used in this paper is an iterative imputation method, missForest, which is related to the random forest approach. Air quality data sets were gathered from five monitoring stations in Kuwait, aggregated to a daily basis. Logarithm transformation was carried out for all pollutant data, in order to normalize their distributions and to minimize skewness. We found high levels of missing values for NO2 (18.4%), CO (18.5%), PM10 (57.4%), SO2 (19.0%), and O3 (18.2%) data. Climatological data (i.e., air temperature, relative humidity, wind direction, and wind speed) were used as control variables for better estimation. The results show that the MAR technique had the lowest RMSE and MAE. We conclude that MI using the missForest approach has a high level of accuracy in estimating missing values. MissForest had the lowest imputation error (RMSE and MAE) among the other imputation methods and, thus, can be considered to be appropriate for analyzing air quality data.

scholarly journals Missing data exploration in air quality data set using R-package data visualisation tools

2020 ◽  
Vol 9 (2) ◽  
pp. 755-763
Author(s):  
Shamihah Muhammad Ghazali ◽  
Norshahida Shaadan ◽  
Zainura Idrus
Keyword(s):  
Air Quality ◽  
Missing Data ◽  
Missing Values ◽  
Missing At Random ◽  
Data Exploration ◽  
Quality Data ◽  
Gap Size ◽  
Data Visualisation ◽  
Data Set ◽  
Air Quality Data

Missing values often occur in many data sets of various research areas. This has been recognized as data quality problem because missing values could affect the performance of analysis results. To overcome the problem, the incomplete data set need to be treated or replaced using imputation method. Thus, exploring missing values pattern must be conducted beforehand to determine a suitable method. This paper discusses on the application of data visualisation as a smart technique for missing data exploration aiming to increase understanding on missing data behaviour which include missing data mechanism (MCAR, MAR and MNAR), distribution pattern of missingness in terms of percentage as well as the gap size. This paper presents the application of several data visualisation tools from five R-packges such as visdat, VIM, ggplot2, Amelia and UpSetR for data missingness exploration.  For an illustration, based on an air quality data set in Malaysia, several graphics were produced and discussed to illustrate the contribution of the visualisation tools in providing input and the insight on the pattern of data missingness. Based on the results, it is shown that missing values in air quality data set of the chosen sites in Malaysia behave as missing at random (MAR) with small percentage of missingness  and do contain long gap size of  missingness.

Particular matter prediction using synergy of multiple source urban big data in smart cities

2021 ◽  
pp. 1-15
Author(s):  
Ali Reza Honarvar ◽  
Ashkan Sami
Keyword(s):  
Air Pollution ◽  
Big Data ◽  
Air Quality ◽  
Smart Cities ◽  
Data Sources ◽  
Quality Data ◽  
Data Set ◽  
Multiple Data Sources ◽  
Multiple Data ◽  
Air Quality Data

At present, the issue of air quality in populated urban areas is recognized as an environmental crisis. Air pollution affects the sustainability of the city. In controlling air pollution and protecting its hazards from humans, air quality data are very important. However, the costs of constructing and maintaining air quality registration infrastructure are very expensive and high, and air quality data recording at one point will not be generalizable to even a few kilometers. Some of the gains come from the integration of multiple data sources, which can never be achieved through independent single-source processing. Urban organizations in each city independently produce and record data relevant to the organization’s goals and objectives. These issues create separate data silos associated with an urban system. These data are varied in model and structure, and the integration of such data provides an appropriate opportunity to discover knowledge that can be useful in urban planning and decision making. This paper aims to show the generality of our previous research, which proposed a novel model to predict Particulate Matter (PM) as the main factor of air quality in the regions of the cities where air quality sensors are not available through urban big data resources integration, by extending the model and experiments with various configuration for different settings in smart cities. This work extends the evaluation scenarios of the model with the extended dataset of city of Aarhus, in Denmark, and compare the model performance against various specified baselines. Details of removing the heterogeneity of multiple data sources in the Multiple Data Set Aggregator & Heterogeneity Remover (MDA&HR) and improving the operation of Train Data Splitter (TDS) part of the model by focusing on the finding more similar pattern of air quality also are presented in this paper. The acceptable accuracy of the results shows the generality of the model.

scholarly journals A Novel Method for Air Quality Data Imputation by Nuclear Norm Minimization

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaobo Chen ◽  
Yan Xiao
Keyword(s):  
Air Quality ◽  
Missing Values ◽  
Nuclear Norm ◽  
Quality Data ◽  
Data Imputation ◽  
Data Set ◽  
Nuclear Norm Minimization ◽  
Imputation Methods ◽  
Norm Minimization ◽  
Air Quality Data

Missing data is a frequently encountered problem in environment research community. To facilitate the analysis and management of air quality data, for example, PM2.5concentration in this study, a commonly adopted strategy for handling missing values in the samples is to generate a complete data set using imputation methods. Many imputation methods based on temporal or spatial correlation have been developed for this purpose in the existing literatures. The difference of various methods lies in characterizing the dependence relationship of data samples with different mathematical models, which is crucial for missing data imputation. In this paper, we propose two novel and principled imputation methods based on the nuclear norm of a matrix since it measures such dependence in a global fashion. The first method, termed as global nuclear norm minimization (GNNM), tries to impute missing values through directly minimizing the nuclear norm of the whole sample matrix, thus at the same time maximizing the linear dependence of samples. The second method, called local nuclear norm minimization (LNNM), concentrates more on each sample and its most similar samples which are estimated from the imputation results of the first method. In such a way, the nuclear norm minimization can be performed on those highly correlated samples instead of the whole sample matrix as in GNNM, thus reducing the adverse impact of irrelevant samples. The two methods are evaluated on a data set of PM2.5concentration measured every 1 h by 22 monitoring stations. The missing values are simulated with different percentages. The imputed values are compared with the ground truth values to evaluate the imputation performance of different methods. The experimental results verify the effectiveness of our methods, especially LNNM, for missing air quality data imputation.

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