Stratified Sampling Research Articles

Prevalence of syphilis among adults and adolescents in five sub-Saharan African countries: findings from Population-based HIV Impact Assessment surveys

HIV and syphilis are common sexually transmitted infections in sub-Saharan Africa. We aimed to investigate the prevalence and distribution of active syphilis while considering HIV status, demographic characteristics, and behavioural characteristics. The Population-based HIV Impact Assessment surveys used a cross-sectional, two-stage, stratified cluster sample design to collect data in Ethiopia, Tanzania, Uganda, Zambia, and Zimbabwe from 2015 to 2018. Eligible participants were aged 15 years and older and provided demographic information, behavioural information, and blood specimens for HIV and syphilis testing. Active syphilis was defined as the presence of both treponemal and non-treponemal antibodies, measured using an antigen-based rapid test. Multivariable logistic regression models with survey weights were applied. The estimated number of participants with active syphilis in each country was calculated by multiplying the survey-weighted syphilis prevalence by the corresponding participant population size from the latest national census data. The total burden across the five countries was obtained by summing these estimates. 102 831 participants enrolled in the five surveys (54 583 [57·6%] participants were female, 48 248 [42·4%] participants were male, 9036 [9·9%] participants were HIV positive). Population-based syphilis prevalence was 0·9% (95% CI 0·7-1·1) in Tanzania and Zimbabwe, 2·1% (1·9-2·4) in Uganda, and 3·0% (2·7-3·4) in Zambia. Overall, an estimated 1 027 615 (95% CI 877 243-1 158 246) participants had active syphilis across the five countries (266 383 HIV-positive and 761 232 HIV-negative individuals). Syphilis prevalence was higher among people living with HIV (range from 2·6% [95% CI 1·1-4·0] in Ethiopia to 9·6% [8·1-11·0] in Zambia) than among those without HIV (range from 0·8% [0·7-1·0] in Tanzania to 2·1% [1·8-2·4] in Zimbabwe). The odds of active syphilis were higher among people living with HIV than in those who were HIV negative (adjusted odds ratio [aOR] range from 2·5 [95% CI 1·8-3·4] in Uganda to 5·9 [3·8-9·2] in Zimbabwe), among divorced, separated, or widowed individuals (aOR range from 1·5 [1·1-2·0] in Uganda to 2·7 [1·7-4·3] in Zimbabwe), and among those reporting two or more sexual partners in the previous 12 months (aOR range from 1·1 [CI 0·8-1·5] in Uganda to 1·9 [1·1-3·3] in Zimbabwe). This study shows the high burden of syphilis in five sub-Saharan African countries, with a correlation between HIV and active syphilis, underscoring the need for integrated sexual health services and targeted diagnosis, prevention, and treatment strategies to address this public health challenge. The President's Emergency Plan for AIDS Relief through the US Centers for Disease Control and Prevention.

Screening for mental disorders in health workers

Introduction: mental health is presented as an essential element in work capacity and productivity, and, similarly, psychosocial risks at work can generate detrimental effects on mental health. Objective: To determine the prevalence of depression, anxiety, and panic disorders among healthcare professionals at the Regional Hospital of Culiacán, Sinaloa, Mexico. Methods: quantitative, observational, descriptive, cross-sectional and analytical study, with stratified probabilistic sampling. Sample of 299 health workers. For data collection, the instrument for detecting anxiety, depression and panic disorders, Patient Health Questionnaire (PHQ-4+PHQ-TP), was used; and for the analysis the statistical program SPSS version 27.Results: it is shown that 59,5 % of the participants are women, 76,3 % work in the morning shift, and 51.8% are single. With 66.9% the nursing job category predominates, 76,6 % have an academic level greater than a bachelor's degree. A quarter of them work two jobs and suffer from chronic illnesses. 25,8 % have been diagnosed with depression, anxiety and/or panic, predominating in the morning shift and in the female gender. Most are assigned to emergency services. The risk of panic predominates at 39,5 % and 53,4 % correspond to nursing staff. Cases of anxiety and depression occur in 47,8 % and 55,7 % respectively in resident doctors. Conclusion: the study shows a high prevalence of mental disorders in health workers in Culiacán, Sinaloa, with significant differences depending on the shift and job category. These findings are consistent with international literature, highlighting the urgent need to implement psychological support programs and improve working conditions.

Assessment Of Effective Factors In E-Learning at Islamic Azad University

The rapid growth of information and communication technology has brought significant changes to the performance of education globally through the use of learning management systems facilitated by e-learning in higher education institutions. Despite perceived advantages such as flexible and widespread access, e-learning still faces challenges like identifying the needs of students, faculty, and staff, as well as delivering quality courses. Furthermore, there is a lack of assessment of existing e-learning initiatives and the determination of critical success factors for quality. This necessitates further research into e-learning practices to fill the identified gaps. This study presents a model for assessing the quality of e-learning systems by modifying and expanding existing frameworks for quality learning with other models and frameworks. A descriptive and exploratory research approach was employed using a cross-sectional survey of 180 respondents from Islamic Azad University, Science and Research Branch. Data were collected through questionnaires and interviews using stratified sampling methods. The validity of the conceptual model was assessed using structural equation modeling and regression analysis. This study revealed that course design, content support, administrative support, user characteristics, organizational factors, and social support impact quality. This research has contributed to the body of knowledge from theoretical, methodological, and practical perspectives.

Practices for introducing complementary foods in Taiwan: A nationwide survey from 2013 to 2016

Background/purposeIntroducing complementary foods to infants is a critical stage in their healthy growth and development process. In this study, we analyzed the feeding habits and choices of caregivers in Taiwan during this essential transition period. MethodsData from the 2013–2016 Nutrition and Health Survey in Taiwan were analyzed. Using a multistage stratified sampling technique, we collected data through questionnaires on the feeding practices, challenges, and information sources associated with complementary feeding. We also investigated the timing of introducing various foods. Certain feeding indicators recommended by the World Health Organization were modified and used for analysis. ResultsAmong 439 caregivers of infants aged 2–24 months, complementary feeding typically began at 5 months, and it primarily began with cereals and pureed foods. At 6–8 months of age, 98.29% of the infants received these foods. Only 48.39% of infants aged 6–24 months consumed eggs or flesh foods. Among the primary challenges for caregivers were concerns regarding infants’ adaptation to new foods (38.2%), refusal of foods by infants (37.1%), and uncertainty regarding which foods to introduce (11.4%). The main sources of information were friends and family (46.9%), the Internet (46.5%), and baby care books (35.6%). Notably, approximately 51% of the respondents used commercial baby foods. ConclusionIn Taiwan, although the majority of infants begin complementary feeding on time, the introduction of eggs and flesh foods is typically delayed. Given the growing reliance on the Internet in the modern age, accurate feeding information should be disseminated online.

Insights for enhancing resilience in prolonged crises: impact of COVID-19 pandemic on nurses’ quality of life

Aims and backgroundThe COVID-19 pandemic has had adverse effects on nurses, impacting them physically, mentally and psychosocially. These effects stem from heightened workloads, fears of contracting a life-threatening illness due...

Epidemiological Profile of Chronic Wounds in an Indian Population: A Community-Based Cross-Sectional Observational Study.

Introduction A wound that has not healed in a timely and organized manner to maintain its anatomical and functional integrity is considered chronic. It can last anywhere from four weeks to over three months and could be caused by trauma, diabetes, vascular disease, infection, or pressure.The primary objective of the study was to determine the prevalence of wounds in a rural and urban community in India, and the secondary objective was to evaluate the effect of various chronic wounds on quality of life (QoL) as assessed by the Short-Form Health Survey-36 (SF-36)questionnaire. Materialsand methods The present study is a cross-sectional analytical study done between June 2022 and December 2023, and a total of 10,003 sample population was screened in Varanasi district, Uttar Pradesh, India. The study involved conducting a door-to-door survey of the population sample under interest based on a stratified sampling technique. During the survey, the epidemiological profile of the sample population, a detailed history, and clinical examination findings were recorded in a proforma. The reports of relevant diagnostic investigations were also recorded. Results The overall prevalence of chronic wounds was 1.89 per 1000 (19/10003) population. The prevalence of wounds in urban areas was 1.57 per 1000 (11/6984) population, while that in rural communities was 2.64 per 1000 (8/3019) population. Of the total 19 patients with chronic wounds, the majority of the patients, i.e., seven each (36.8%), had diabetic foot ulcers (DFUs) and neglected/uncared trauma as the etiology for chronic wounds. The remaining five (5.3%) patients were equally divided between cellulitis, venous ulcers, trophic ulcers, tubercular ulcers, and malignancy as the etiology for chronic wounds. The QoL data suggested that 11 (57.9%)patients reported their general health status as fair with wounds, followed by five (26.3%) reporting their general health status as poor. Only three (15.8%) of the patients with wounds reported their general health condition as good. There was no significant difference between the QoL of rural and urban patients with chronic wounds. The overall prevalence of wounds has decreased from 15.03 to 1.89 per 1000 people in the survey locality. The switch from opting for home-based remedies to supervised care under the clinician (be it in a private or public setting) clearly indicates raised awareness regarding the management of wounds, and with time, people have shown an increased interest in healthcare facility treatment under supervision over adopting home remedies for wound treatment. The same domain may be attributed to the prompt management and efficacy of the management protocols by the treating physicians in India. Conclusion The findings of the present study regarding the incidence and prevalence of chronic wounds in connection to demographic factors are important when allocating resources and making healthcare plans. The present study conveys a clear message to healthcare practitioners about the necessity of carrying out large-scale epidemiological research on this topic and offers a solid foundation for future studies.

Fatal and Nonfatal Firearm Injury Rates by Race and Ethnicity in the United States, 2019 to 2020.

Racial disparities in firearm injury death in the United States are well established. Less is known about the magnitude of nonfatal and total firearm injury. To combine health care data with death certificate data to estimate total firearm injuries in various racial and ethnic groups. Retrospective, cross-sectional study. Fatal injury data were collected from the Centers for Disease Control and Prevention. Data on nonfatal injuries were collected from the Nationwide Emergency Department Sample (NEDS), a 20% stratified sample of U.S. emergency department visits, weighted to provide national estimates for the United States, 2019 to 2020. All firearm injuries and deaths in the United States. Race and ethnicity were classified into 5 mutually exclusive categories: Asian or Pacific Islander, Black, Hispanic, Native American, and White. International Classification of Diseases, 10th Revision codes were used to classify firearm injury intent. Incidence of fatal and nonfatal injury in the U.S. population and case-fatality ratios (CFRs). There were 252 376 total firearm injuries, including 84 908 deaths from firearm injures. Of all firearm injuries, 37.8% were unintentional, 37.3% were assault related, 21.0% were self-harm, and 1.3% were law enforcement associated. Self-harm had the highest CFRs (90.9% overall). Unintentional injuries accounted for just 1021 (1.2%) deaths but 94 433 (56.4%) of nonfatal injuries. Rates of self-harm were highest among White persons (11.0 per 100 000 population in 2020) followed by Native Americans (8.6 per 100 000). Rates of assault were highest among Black persons (70.1 per 100 000), as were unintentional injuries (56.1 per 100 000). Findings are limited by the accuracy of discharge coding in NEDS, particularly regarding injury intent and patient race and ethnicity. From 2019 to 2020, the total burden of firearm injuries amounts to an average of 1 injury every 4 minutes and 1 death every 12 minutes in the United States. Racial disparities in firearm injury death are mirrored in nonfatal injury. None.

ICT Integration in Secondary Schools: Evaluating Ease of Use and Perceived Benefits for Effective Teaching and Learning

This research investigates the integration of Information and Communication Technology (ICT) in secondary schools, focusing on educators' perceptions of its ease of use and perceived benefits for effective teaching and learning. Utilizing a quantitative approach with a survey methodology, data was collected from 60 secondary schools across Lahore and Gujranwala districts, involving 310 secondary school educators (144 males and 166 females). A proportionate stratified sampling technique was employed, and a modified version of the QICT (Questionnaire on the Integration of ICT) was used to assess teachers' views on ICT integration. Five experts validated the instrument with a reliability coefficient of 0.789. Results indicate that ICT integration is crucial for enhancing teaching and learning in secondary schools. Teachers with ICT-related qualifications demonstrated a more significant influence on classroom ICT usage. The study found that teachers generally perceived ICT integration as easy and beneficial, noting improved teaching effectiveness and student engagement. Educators with advanced ICT skills were more effective in incorporating technology into their teaching practices. Overall, the research underscores the importance of ICT in creating dynamic and effective learning environments in secondary education.

BOARD ATTRIBUTES AND SUSTAINABILITY REPORTING OF LISTED FIRMS IN NIGERIA

This study investigates the impact of board attributes on sustainability reporting among listed firms in Nigeria from 2013 to 2022, using a correlational research design. The research population encompasses all Nigerian listed firms, with a stratified sampling technique deemed appropriate for the study. Secondary data were sourced from the audited annual reports and accounts of sampled firms available on the Nigerian Exchange Group (NGX) website. The analysis of the extracted panel data was conducted using multiple regression techniques with STATA version 13. The findings of the study reveal that board size, gender diversity, and independence positively influence sustainability reporting, while board commitment has a negative impact on sustainability reporting. Consequently, the study recommends that the management of Nigerian listed firms should view large and diverse boards as an asset for promoting sustainability reporting. Such boards, comprising experienced and knowledgeable members, are more likely to make effective decisions on sustainability-related issues. Additionally, the presence of women on boards should be considered a valuable factor in encouraging comprehensive financial reporting, which includes qualitative and quantitative information on the social, environmental, and economic activities of the business for stakeholders.

The Factors Influencing Supply Chain Performance in Tanzanian Public Procuring Entities: The Mediating Role of Supplier-Buyer Relationships

Academia's current emphasis on supply chain performance highlights the significance of information sharing as a mediator and the supplier-buyer relationship as a moderator. Nevertheless, the examination into the intermediate effects of the supplier-buyer relationship has been relatively neglected. This research examined the factors affecting supply chain performance, emphasizing the mediating role of the supplier-buyer relationship to address the existing knowledge gap in the literature. The research included both descriptive and explanatory methodologies. The positivist research paradigm and stratified sampling method were employed to obtain a sample size of 167 respondents. The data were collected through a questionnaire and an analysis of relevant documents. The collected data was examined using Partial Least Squares Structural Equation Modeling, facilitated by SmartPLS 4, a tool for conducting inferential statistical analysis. The analyzed data on respondents' profiles underwent descriptive statistical analysis using IBM SPSS Statistics Version 26. The research findings indicate that supply chain performance is affected by information sharing, strategic procurement planning, and the relationship between suppliers and buyers. The statistical significance of strategic procurement planning and information sharing indicates that buyers and suppliers rely on these practices to improve supply chain performance. The results provide definitive evidence validating the accuracy of the proposed research model within the domain of decision-making, specifically regarding the prioritization of investments to improve supply chain performance.

Navigating the Adoption of Islamic Banking in the Base of Pyramid Market of Pakistan

The purpose of this research paper is to examine the adoption of Islamic banking (AIB) in the Bottom of the Pyramid (BoP) Market of Pakistan. The study used theory of planned behavior to hypothesize the relationship of the attitude (ATT), subjective norms (SN), perceived behavioral control (PBC), and Islamicity of the Product (IoP) on adoption of Islamic Banking (IB). Exploratory research design was used with a total of 400 questionnaires were distributed using a multi-staged stratified sampling (random sampling within each stratum) approach of which 320 usable questionnaires were returned representing 80 percent response rate. Partial Least Square Structural Equation Modeling (PLS-SEM) approach was used to analyze the hypothesized relationship of the conceptual framework. Results indicated that attitude (ATT), subjective norms (SN), and Islamicity of product (IoP) explained notable effect on the adoption of Islamic banking comparatively the perceived behavioral control (PBC). The overall effect of ATT, SN, PBC, and IoP explained 39.3 percent on AIB within the context of BoP. The adoption of Islamic banking counts the aforementioned variables with their countable effects. The inclusive outreach and features explaining the Islamicity of the financial products can enhance the span Islamic banking market share. Islamic banking over the past decade has witnessed tremendous growth in Asian countries due to innovative financial offerings based on the Sharia Principles of Islam. This study contributed on how the Islamic financial products can be penetrated in the low-income markets like Pakistan with its specific focus in Southern region of the Punjab province. The theoretical framework of the study has demonstrated how the customer closely associated behaviors navigate the adoption of the Islamic banking.

Barriers to Communication in Undergraduate Medical Education: Perspectives of Students From Karnataka, India.

Background Communication barriers in medical education can impede learning. Understanding these barriers from students' perspectives is crucial for developing effective solutions. The objectives of this study were to identify the barriers to communication in undergraduate medical education and their solutions from students' perspectives as well as to determine the demographic factors associated with these barriers. Materials and methods A cross-sectional study was conducted from May 2018 to July 2019 among undergraduate students at a medical college in Karnataka. Using a stratified sampling method, data was collected from 400 students via a pretested semi-structured questionnaire. The data was analyzed using descriptive statistics, and logistic regression analysis was performed to determine the association between demographic factors and barriers to communication. Results Students identified several communication barriers, primarily in the domains of language, environment, psychology, and teacher-related issues. Key barriers in theory classes included the use of medical jargon, overcrowding, faulty microphones, absent-mindedness, peer pressure, fast-paced teaching, monotonous sessions, and information overload. In practical classes, barriers were overcrowding, absent-mindedness, and fast-paced teaching, and for clinical case discussions, barriers included difficulty understanding the local language, overcrowding, and leg pain. Proposed solutions by students for theory classes included simpler explanations, smaller batches, microphone maintenance, interactive lectures, and breaks between classes. For practical classes, solutions were smaller practical batches, interactive sessions, and simpler explanations of topics, while for case discussion, solutions included optional local language classes, smaller groups, and better seating arrangements. Conclusion This study highlights key communication barriers in medical education and underscores the influence of demographic factors such as gender and academic year. The solutions proposed by the students are practical and could enhance communication and the overall educational experience if implemented in medical colleges across India.

The Influence of Using Instagram @Official USU Account on Image and Public Trust at Universitas Sumatera Utara Medan

This study aims to determine the effect of the use of the Instagram account @official.usu on the image and public trust at the University of North Sumatra in Medan City and to determine the level of influence between the use of the Instagram account @official.usu and the image and public trust at the University of North Sumatra in Medan City. This research method uses a quantitative approach and is carried out in Medan Baru District which consists of 6 Villages. The theories used are public relations theory, new media, image and trust. Indicators of Instagram use consist of Context, Communication, Collaboration, and Connection, indicators of image consist of Personality, Reputation, Value, and Corporate Identity, indicators of trust consist of Ability, Integrity, and Benevolence. Sampling was carried out using the Stratified Proportional Sampling and Cluster Random Sampling techniques with a sample size of 400 people. Data were collected through Google Forms which were distributed to respondents. The research data were analyzed using the single table method, cross table, Spearman Rank hypothesis test, and correlation coefficient analysis

Role of Iodine Status and Lifestyle Behaviors on Goiter among Children and Adolescents: A Cross-Sectional Study in Zhejiang Province, China.

Iodine deficiency is a well-established cause of goiter, while the impact of lifestyle factors on goiter development remains underexplored. The study aims to explore the associations between iodine status, lifestyle factors, and the prevalence of goiter among children and adolescents in Zhejiang Province, China. A cross-sectional survey was conducted in 2022 using a stratified multistage sampling, involving 2261 children aged 6-17. Among these 1562 participants underwent both urinalysis and thyroid ultrasound. Lifestyle factors were assessed through self-reported questionnaires. The prevalence of goiter in the study population was 10.8%. A high urinary iodine concentration (UIC) (>300 μg/L) was significantly associated with a decreased risk of goiter (OR = 0.49, 95%CI: 0.27-0.88). Excessive recreational screen time and a high frequency of dining out were associated with an increased Tvol, while adequate physical activity and sleep were inversely associated with goiter risk, while the combined effect of high UIC and healthy lifestyle showed a protective effect against goiter. Ensuring adequate iodine status and promoting healthy lifestyles are crucial for preventing goiter and enhancing thyroid health in children and adolescents, suggesting that public health strategies should integrate nutritional and lifestyle interventions.

Unveiling Brand Identity A Semiotic Exploration of Logo Design in Pakistani Clothing Brands

In the competitive textile market, each brand employs a unique logo or icon to distinguish itself from competitors. A logo acts as a brand's visual identity, conveying its uniqueness and intended message to consumers. Therefore, creating an effective logo is crucial for designers, as it significantly influences consumer perception. This research uses a semiotic analysis based on Kress and van Leeuwen's (2002) multimodality framework to examine the logos of two leading Pakistani clothing brands, including Khaadi and Junaid Jamshed. The study investigates how these logos impact consumer relationships with the brands, revealing that each logo is designed to communicate the brand's distinct message. Factors such as colour schemes, logos, font, shape, words, and the inclusion of popular personalities in advertisements are essential in shaping consumer perceptions and preferences. The research involved stratified sampling to collect data, ensuring a representative analysis of consumer views. The findings indicate that well-designed logos and strategic branding elements are crucial for a strong brand-consumer connection. These elements significantly affect consumer loyalty and choice, underscoring the importance of effective logo design in building a positive brand image and influencing consumer behaviour.

Innovative IoT Solutions for Enhanced Patient Health Monitoring and Healthcare Efficiency in Hospitals

Abstract: Hospitals worldwide have been grappling with overcrowding, a challenge that became particularly acute during the COVID-19 pandemic. Implementing IoT devices can enhance hospital efficiency and reduce the risk of infection for healthcare providers. With IoT, remote health monitoring becomes possible, leading to more timely and improved patient care. The research employs a stratified sampling method, with survey questionnaires distributed to gather data. Based on this data, a proposed system will be developed to evaluate its feasibility and effectiveness. As IoT technology advances, the system is expected to evolve, providing users with greater confidence and ease of use. The goal of this research and proposal is to implement a solution that enhances health monitoring in hospitals, ultimately offering patients better and more timely healthcare.

Financial incentives and work commitment among Ghanaian COVID-19 frontline healthcare workers

The influence of financial incentives on work commitment is widely studied, yet the effects of financial incentives on healthcare workers ‘commitment in a pandemic situation remains underexplored. Drawing on Ghana government’s financial incentives policy as part of its COVID-19 response, we examined the relationship between Financial Incentives (GFI) and work commitment [Adherence to Work Ethics (ATWE), Task Involvement (TI) and Organisational Citizenship Behaviours (OCB)] among COVID-19 Frontline Healthcare Workers (FHWs), and the mediating effect of Job Satisfaction (JS). Of the 187 COVID-19 FHWs in two sampled hospitals in the Ashanti region, purposive and stratified sampling techniques were used to select 126 respondents from whom data were gathered using structured questionnaires. SPSS and Smart PLS Structural Equation Modelling (SEM) were used to analyse the data. Baron and Kenny's (1986) causal-effect model of mediation analysis was used to determine the mediating role of Job Satisfaction (JS). GFI predicted ATWE positively but insignificantly. However, GFI had a significant positive effect on TI, OCB and JS. JS had no significant mediating effect on the relationship between GFI and ATWE. However, JS partially mediated the relationship between GFI, TI, and OCB. These findings offer critical insights for effectively managing the healthcare workforce during pandemics.

Effectiveness of Literacy and Numeracy Drive Application An Analytical Study Based on Teachers’ Perceptions and Students’ Learning Achievements in Punjab

The study’s objective was to discover head teachers’ and teachers’ perceptions about the role and students’ achievement trends in Literacy and Numeracy Drive (LND) data in mathematics and English except Urdu. LND as an application was a step taken by the Government of Punjab, Pakistan, which started in 2015 and continues in the government primary section schools for grade three students of the province. The population comprised all primary section heads and teachers in 53 boy’s public schools, consisting of 390 head teachers and teachers using a stratified sampling technique. The study’s nature was quantitative and involved a survey method for data collection. The achievements of students’ trends were analysed. The data collected were analysed using Mean as statistics with the help of the Statistical Package for Social Sciences (SPSS). The data revealed that head teachers and teachers have positive perceptions of English and mathematics, with high perceptions of mathematics. The students’ trends were also more positive in mathematics. It was recommended that mathematics in LND is more favourable than English. A study may be conducted for boys and girls separately by considering all three subjects of LND in Punjab province.

Defying the flat-Earth myth: Soil organic carbon monitoring in topographically complex temperate pasture landscapes

Soil sampling design to capture the spatiotemporal variability of soil organic carbon (SOC) stocks in complex landscapes is challenged by the influence of topographical features on primary production, animal behaviour, and carbon and nutrient return to grasslands. Here we explore a range of approaches for streamlining the sampling process using measures of SOC stock data (2003, 2020, 2021) from a long-term hill-country fertilizer experiment. The stepwise procedure included a) evaluation of sampling efficiency between stratified and random soil sampling designs to capture spatial variability of SOC stocks, b) semi-parametric regression analysis to evaluate the representativeness of certain strata (e.g. medium slopes), c) exploring the appropriateness of using shallow SOC stock estimates to represent the full sampling depth, and d) the use of a process-based model to determine expected SOC stock changes and temporal variability to estimate the number of representative soil samples required to achieve a significant minimum change. Our analyses suggest that a) the stratified sampling design was more efficient reflected in the number of samples required to identify 5 % deviation in SOC stocks, b) estimates obtained on the medium slope were a reasonable approximation of the SOC stocks and its spatial variation across the farmlets, c) shallow (0–75 mm) SOC stock estimates from an adjusted regression model offered an accurate inference of its vertical distribution (0–300 mm), and d) the Grass-NEXT model provided insights on where more intensive sampling is required to detect a significant minimum change in SOC stocks over time. Tailored, stratified soil sampling and context-specific strategies, such as using representative strata and shallow sampling as effective steps for estimating SOC stocks and addressing data gaps, are crucial for simplifying monitoring and minimizing the cost of on-farm soil sampling designs in topographically complex landscapes covered by long-term pastures.

Stratified sampling for roots biomass quantification in shifting cultivation in Amazon Brazil

Several countries have been paying attention to carbon stocks and balances in the soil, a characteristic related to land management and use. Among the biomes that have great participation in the maintenance of these stocks, the Amazon biome stands out, which has great diversity by area. With the advances in markets aimed at buying carbon credits, estimates of the values of these stocks are highly susceptible to the intrinsic characteristics of the location. In order to solve these problems, several soil sampling techniques have been used to estimate these values. However, soil sampling techniques vary greatly in the amount of soil sampled, directly impacting the values of these estimates. In this sense, the present work aims to evaluate the point and interval estimates of carbon stocks in the soil in a peripheral region of the Brazilian Amazon, in the state of Maranhão. For this, three soil sampling techniques were compared, the large monolith (LM), the small monolith (SM) and the auger (RA). Considering a stratified sampling plan (STR), in which the different sampled depths are considered as strata, its efficiency was compared to a simple random sampling (SRS) and its amplitudes with the simulation through the Bootstrap technique. The samples were obtained by washing the samples and separating them into < 2mm and > 2mm for two biological groups (babassu roots and other roots). For interval estimates with the LM collection method, roots larger than 2 mm have a total of 2.56 to 4.62 t ha–1, and for smaller roots, 1.67 to 4.33 t ha–1. As for babassu roots, these values ranged from 0.38 to 1.44 t ha–1 and those smaller than 2 mm from 0.86 to 2.43. In contrast, the LM collection method can be replaced by SM and RA only for thick roots (> 2 mm). Regarding the STR sampling plan, the variance of the total was reduced in relation to the SRS. The bootstrap technique managed to reduce the amplitude of the intervals to the total, showing an improvement in accuracy. Therefore, estimates of carbon stocks can be made for the RA method for stored carbon, but the method for carbon that will return to the atmosphere the LM method is the most suitable.