The importance of input data quality and quantity in climate field reconstructions – results from the assimilation of various tree-ring collections

Abstract. Differences between paleoclimatic reconstructions are caused by two factors: the method and the input data. While many studies compare methods, we will focus in this study on the consequences of the input data choice in a state-of-the-art Kalman-filter paleoclimate data assimilation approach. We evaluate reconstruction quality in the 20th century based on three collections of tree-ring records: (1) 54 of the best temperature-sensitive tree-ring chronologies chosen by experts; (2) 415 temperature-sensitive tree-ring records chosen less strictly by regional working groups and statistical screening; (3) 2287 tree-ring series that are not screened for climate sensitivity. The three data sets cover the range from small sample size, small spatial coverage and strict screening for temperature sensitivity to large sample size and spatial coverage but no screening. Additionally, we explore a combination of these data sets plus screening methods to improve the reconstruction quality. A large, unscreened collection generally leads to a poor reconstruction skill. A small expert selection of extratropical Northern Hemisphere records allows for a skillful high-latitude temperature reconstruction but cannot be expected to provide information for other regions and other variables. We achieve the best reconstruction skill across all variables and regions by combining all available input data but rejecting records with insignificant climatic information (p value of regression model >0.05) and removing duplicate records. It is important to use a tree-ring proxy system model that includes both major growth limitations, temperature and moisture.

Download Full-text

The importance of input data quality and quantity in climate field reconstructions – results from a Kalman filter based paleodata assimilation method

10.5194/cp-2019-80 ◽

2019 ◽

Author(s):

Jörg Franke ◽

Veronika Valler ◽

Stefan Brönnimann ◽

Raphael Neukom ◽

Fernando Jaume Santero

Keyword(s):

Sample Size ◽

Tree Ring ◽

Input Data ◽

Small Sample ◽

Screening Methods ◽

Temperature Sensitive ◽

Data Sets ◽

Large Sample Size ◽

Spatial Coverage ◽

Reconstruction Quality

Abstract. Differences between paleoclimatic reconstructions are caused by two main factors, the method and the input data. While many studies compare methods, we will focus in this study on the consequences of the input data choice in a state-of-the-art paleo data assimilation approach. We evaluate reconstruction quality based on three collections of tree-ring records: (1) 54 of the best temperature sensitive tree-ring chronologies chosen by experts; (2) 415 temperature sensitive tree-ring records chosen less strictly by regional working groups and statistical screening; (3) 2287 tree-ring series that are not screened for climate sensitivity. The three data sets cover the range from small sample size, small spatial coverage and strict screening for temperature sensitivity to large sample size and spatial coverage but no screening. Additionally, we explore a combination of these data sets plus screening methods to improve the reconstruction quality. Neither a large, unscreened collection of proxy data nor the small expert selection leads to the best possible climate field reconstruction. A large collection of unscreened data leads to a poor reconstruction skill. The few best temperature proxies allow for a skillful high latitude temperature reconstruction but fail to provide improved reconstructions for other regions and other variables. We achieve the best reconstruction skill across all variables and regions by combing all available input data but rejecting records with small, insignificant information and removing duplicate records. In case of assimilating tree ring proxies, it appeared to be important to use a tree-ring proxy system model that includes both major growth limitations, temperature and moisture.

Download Full-text

Somatic Acupoint Stimulation for Cancer-Related Sleep Disturbance: A Systematic Review of Randomized Controlled Trials

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2020/2591320 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Xian-Liang Liu ◽

Hui Lin Cheng ◽

Simon Moss ◽

Carol Chunfeng Wang ◽

Catherine Turner ◽

...

Keyword(s):

Systematic Review ◽

Sleep Disturbance ◽

Sample Size ◽

Methodological Quality ◽

Outcome Measurement ◽

Small Sample ◽

Large Sample Size ◽

Intervention Protocol ◽

Acupoint Stimulation

Aim. The aim of this systematic review was to analyze and synthesize available evidence for the effects of somatic acupoint stimulation (SAS) on cancer-related sleep disturbance in adults with cancer. Methods. Nine databases and four clinical trial registries were searched from their inception to July 2019 to identify potential articles and registered trials. Two authors independently extracted data and appraised the methodological quality of the included studies. The included studies could not be subjected to meta-analysis due to the significant variations in SAS intervention protocols and outcome measurement instruments. This systematic review therefore reported the results of the included trials narratively. Results. Seven studies were identified, which involved 906 cancer patients. SAS protocols varied across trials without an optimal evidence-based standard intervention protocol to manage cancer-related sleep disturbance. Sanyinjiao (SP6) was the most commonly selected acupoint. Manual acupuncture was typically 15–30 min in duration and was conducted once a day or once a week for a period of 1–5 weeks, whereas self-administered acupressure was typically 1–3 min in duration per point and was conducted once a day, such as during night time before going to bed, for a period of 1–5 months. The results indicated that SAS could potentially relieve cancer-related sleep disturbance and improve quality of life. Mild adverse effects were reported in three of the included studies, but none of them performed a causality analysis to clarify the association between the reported adverse events and the intervention. Conclusions. This systematic review showed that SAS is a useful approach to relieving cancer-related sleep disturbance. However, research evidence on SAS for managing cancer-related sleep disturbance has not been fully conclusive due to the limited number of existing clinical studies with relatively small sample size and suboptimal methodological quality. Clinical trials with large sample size and robust methodology are warranted in future research.

Download Full-text

Acupuncture for Chronic Pain-Related Insomnia: A Systematic Review and Meta-Analysis

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2019/5381028 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10

Author(s):

Fushui Liu ◽

Jianyu You ◽

Qi Li ◽

Ting Fang ◽

Mei Chen ◽

...

Keyword(s):

Chronic Pain ◽

Sample Size ◽

Small Sample Size ◽

Meta Analysis ◽

Sham Acupuncture ◽

Small Sample ◽

Control Group ◽

Large Sample Size ◽

Cure Rate ◽

Significant Difference

Objectives. Acupuncture has been widely used to relieve chronic pain-related insomnia (CPRI). However, the efficacy of acupuncture for CPRI is uncertain. The purpose of this study was to evaluate the efficacy of acupuncture for CPRI. Methods. Seven electronic databases were searched from inception to December 2018. Randomized controlled trials (RCTs) were included if acupuncture was compared to sham acupuncture or conventional drug therapies for treating CPRI. Two reviewers screened each study and extracted data independently. Statistical analyses were conducted by RevMan 5.3 software. Results. A total of nine studies involving 944 patients were enrolled. The pooled analysis indicated that acupuncture treatment was significantly better than control group in improving effective rate (OR = 8.09, 95%CI = [4.75, 13.79], P < 0.00001) and cure rate (OR = 3.17, 95%CI = [2.35, 4.29], P < 0.00001), but subgroup analysis showed that there was no statistically significant difference between acupuncture and sham acupuncture in improving cure rate (OR =10.36, 95% CI [0.53, 201.45], P=0.12) based on one included study. In addition, meta-analysis demonstrated that acupuncture group was superior to control group in debasing PSQI score (MD = -2.65, 95%CI = [-4.00, -1.30], P = 0.0001) and VAS score (MD = -1.44, 95%CI = [-1.58, -1.29], P < 0.00001). And there was no significant difference in adverse events (OR =1.73, 95%CI = [0.92, 3.25], P =0.09) between the two groups. Conclusions. Acupuncture therapy is an effective and safe treatment for CPRI, and this treatment can be recommended for the management of patients with CPRI. Due to the low quality and small sample size of the included studies, more rigorously designed RCTs with high quality and large sample size are recommended in future.

Download Full-text

A fistful of shells: amplifying sclerochronological and palaeoclimate signals from molluscan death assemblages

Geological Magazine ◽

10.1017/s0016756809990033 ◽

2009 ◽

Vol 146 (6) ◽

pp. 917-930 ◽

Cited By ~ 7

Author(s):

S. HELAMA ◽

J. K. NIELSEN ◽

M. MACIAS FAURIA ◽

I. VALOVIRTA

Keyword(s):

Sample Size ◽

Tree Ring ◽

Small Sample Size ◽

Low Frequency ◽

Small Sample ◽

Pearl Mussel ◽

Climate Signal ◽

Growth Variability ◽

Low Frequency Variability ◽

The Individual

AbstractA growing body of literature is using sclerochronological information to infer past climates. Sclerochronologies are based on series of skeletal growth records of molluscs that have been correctly aligned in time. Incremental series are obtained from a number of shells to assess the temporal control and improve the climate signal in the final chronology. Much of the sclerochronological theory has been adopted from tree-ring science, due to the longer tradition and more firmly established concepts of chronology construction in dendrochronology. Compared to tree-ring studies, however, sclerochronological datasets are often characterized by relatively small sample size. Here we evaluate how effectively palaeoclimatic signal can be extracted from such a suite of samples. In so doing, the influences of the very basic methods that are applied in nearly every sclerochronological study to remove the non-climatic growth variability prior to palaeoclimatic interpretations, are ranked by their capability to amplify the desired signal. The study is performed in the context of six shells that constitute a bicentennial growth record from annual shell increments of freshwater pearl mussel. It was shown that when the individual series were detrended using the models set by the mean or the median summary curves for ageing (that is, applying Regional Curve Standardization, RCS), instead of fitting the ageing mode statistically to each series, the resulting sclerochronology displayed more low-frequency variability. Consistently, the added low-frequency variability evoked higher proxy–climate correlations. These results show the particular benefit of using the RCS method to develop sclerochronologies and preserve their low-frequency variations. Moreover, calculating the ageing curve and the final chronology by median, instead of mean, resulted in an amplified low-frequency climate signal. The results help to answer a growing need to better understand the behaviour of the sclerochronological data. In addition, we discuss the pitfalls that may potentially disrupt palaeoclimate signal detection in similar sclerochronological studies. Pitfalls may arise from shell taphonomy, water chemistry, time-variant characters of biological growth trends and small sample size.

Download Full-text

Are methylation beta-values simplex distributed?

10.1101/753459 ◽

2019 ◽

Author(s):

Lara Nonell ◽

Juan R González

Keyword(s):

Dna Methylation ◽

Sample Size ◽

Microarray Data ◽

Regression Models ◽

Real Data ◽

Small Sample ◽

Beta Regression ◽

Data Sets ◽

Methylation Data ◽

Simplex Distribution

AbstractDNA methylation plays an important role in the development and progression of disease. Beta-values are the standard methylation measures. Different statistical methods have been proposed to assess differences in methylation between conditions. However, most of them do not completely account for the distribution of beta-values. The simplex distribution can accommodate beta-values data. We hypothesize that simplex is a quite flexible distribution which is able to model methylation data.To test our hypothesis, we conducted several analyses using four real data sets obtained from microarrays and sequencing technologies. Standard data distributions were studied and modelled in comparison to the simplex. Besides, some simulations were conducted in different scenarios encompassing several distribution assumptions, regression models and sample sizes. Finally, we compared DNA methylation between females and males in order to benchmark the assessed methodologies under different scenarios.According to the results obtained by the simulations and real data analyses, DNA methylation data are concordant with the simplex distribution in many situations. Simplex regression models work well in small sample size data sets. However, when sample size increases, other models such as the beta regression or even the linear regression can be employed to assess group comparisons and obtain unbiased results. Based on these results, we can provide some practical recommendations when analyzing methylation data: 1) use data sets of at least 10 samples per studied condition for microarray data sets or 30 in NGS data sets, 2) apply a simplex or beta regression model for microarray data, 3) apply a linear model in any other case.

Download Full-text

Gender Wise Distribution of Income Using L-Moments Method

Communication Society and Media ◽

10.22158/csm.v2n1p29 ◽

2019 ◽

Vol 2 (1) ◽

pp. 29

Author(s):

Muhammad Alam ◽

Saeed Ullah Jan ◽

Alam Zeb

Keyword(s):

Income Distribution ◽

Sample Size ◽

Small Sample Size ◽

Small Sample ◽

Parameters Estimation ◽

Large Sample Size ◽

Unknown Parameters ◽

Moments Method ◽

L Moments ◽

Distribution Of Income

<em>The main purpose of this work is to explore the income distribution of both male and female in Pakistan over the period of 2010-2011. For this purpose, the lognormal distribution with known parameters is used as a model and its unknown parameters are estimated by three methods that are likelihood, moments and L-moments. The results show that citizens of Pakistan are not equal in income and the probability plot suggested that the income of the male is greater than that of a female in Pakistan. Moreover, for small sample size, the best method of parameters estimation is the L-moments, while, for large sample size the best method is a maximum likelihood. Findings of the study suggest that suitable policy is required to maintain equality in income distribution in the country. It will consequently reduce the gap among rich and poor and will certainly improve social welfare.</em>

Download Full-text

On the Subrange and Its Application to the R-Chart

Applied Sciences ◽

10.3390/app112411632 ◽

2021 ◽

Vol 11 (24) ◽

pp. 11632

Author(s):

En Xie ◽

Yizhong Ma ◽

Linhan Ouyang ◽

Chanseok Park

Keyword(s):

Standard Deviation ◽

Sample Size ◽

Correction Factor ◽

Relative Efficiency ◽

Least Squares Method ◽

Small Sample ◽

Large Sample Size ◽

Large Sample ◽

Sample Range ◽

Conventional Sample

The conventional sample range is widely used for the construction of an R-chart. In an R-chart, the sample range estimates the standard deviation, especially in the case of a small sample size. It is well known that the performance of the sample range degrades in the case of a large sample size. In this paper, we investigate the sample subrange as an alternative to the range. This subrange includes the range as a special case. We recognize that we can improve the performance of estimating the standard deviation by using the subrange, especially in the case of a large sample size. Note that the original sample range is biased. Thus, the correction factor is used to make it unbiased. Likewise, the original subrange is also biased. In this paper, we provide the correction factor for the subrange. To compare the sample subranges with different trims to the conventional sample range or the sample standard deviation, we provide the theoretical relative efficiency and its values, which can be used to select the best trim of the subrange with the sense of maximizing the relative efficiency. For a practical guideline, we also provide a simple formula for the best trim amount, which is obtained by the least-squares method. It is worth noting that the breakdown point of the conventional sample range is always zero, while that of the sample subrange increases proportionally to a trim amount. As an application of the proposed method, we illustrate how to incorporate it into the construction of the R-chart.

Download Full-text

Risk Assessment of Intermittent and Continuous Nasogastric Enteral Feeding Methods in Adult Inpatients: A Meta-Analysis

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2021/8875002 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Guang Yang ◽

Bojun Zheng ◽

Yi Yu

Keyword(s):

Sample Size ◽

Group Size ◽

Enteral Feeding ◽

Small Sample Size ◽

Meta Analysis ◽

Small Sample ◽

Size Group ◽

Large Sample Size ◽

Increased Risk ◽

Feeding Methods

Diarrhea and pneumonia are common and serious complications in hospitalized patients requiring nasogastric enteral feeding. Our study aimed to compare the risk of diarrhea and pneumonia between intermittent nasogastric enteral feeding (IEF) and continuous nasogastric enteral feeding (CEF). We systematically searched PubMed, Web of Science, and Cochrane for relevant articles published from August 9, 1992, to September 1, 2019. A total of 637 IEF and CEF patients were included in our meta-analysis. Odds ratios (ORs) with associated 95% confidence intervals (CIs) were calculated to estimate the effects of diarrhea and pneumonia. We showed that hospital patients that required IEF had an increased risk of diarrhea compared with CEF. In the subgroup analyses, similar conclusions were identified in the non-China group and small sample size group (size < 100). However, our results showed no significant differences in the China group or large sample size group (size ≥ 100). Furthermore, our analysis showed that no significant association was observed for the risk of pneumonia between IEF and CEF patients. For inpatients requiring nasogastric enteral feeding, CEF is a better method of enteral nutrition compared with IEF, of which patients experience a significantly increased risk of diarrhea.

Download Full-text

Socially responsible investment sukuk (Islamic bond) development in Malaysia

Qualitative Research in Financial Markets ◽

10.1108/qrfm-09-2019-0117 ◽

2020 ◽

Vol 12 (4) ◽

pp. 599-619

Author(s):

Mahfuzur Rahman ◽

Che Ruhana Isa ◽

Ginanjar Dewandaru ◽

Mohamed Hisham Hanifa ◽

Nazreen T. Chowdhury ◽

...

Keyword(s):

Sample Size ◽

Small Sample Size ◽

Socially Responsible Investment ◽

Small Sample ◽

Future Research ◽

Large Sample Size ◽

Structured Interviews ◽

Socially Responsible ◽

Content Type ◽

Responsible Investment

Purpose This study aims to explore the underlying issues related to the development of socially responsible investment (SRI) sukuk in Malaysia. It identifies factors attracting investors and issuers, as well as challenges for the development of SRI sukuk (Islamic bond) in Malaysia. Design/methodology/approach This study conducted semi-structured interviews to collect data from the institutional investors, SRI sukuk issuers and arrangers, as well as researchers. A total of 19 experts were approached in which 10 participated in the interview. The thematic analysis technique is used to report the findings. Findings This study uncovers that social contribution through business activities (i.e. investment in the education sector) is the key motivational drivers for the investors and issuers. Besides, investment risks, lack of performance measurement standards, high transaction costs, risks of return, shortage of enough Islamic bonds, investors’ confidence and lack of awareness are the major challenges for the development of SRI sukuk instruments. Research limitations/implications Due to the challenges in finding experts on this subject matter, this study was able to manage only 10 interviews from the participants, which is a small sample size. However, the findings of this study cannot be ignored. Future research should carry out with a large sample size (i.e. at least 30 interviews) to validate the current findings. Originality/value This study is among the pioneer in Malaysia, which explores the influencing factors of selecting Islamic bonds as an investment option. This paper provides some valuable implications for investors through discovering the challenges for the growth of SRI sukuk in Malaysia, which can also be applicable in a global setting.

Download Full-text

Meta-Analysis and Forest Plots for Sustainability of Heavy Load Carrier Equipment Used in the Industrial Mining Environment

Sustainability ◽

10.3390/su13158672 ◽

2021 ◽

Vol 13 (15) ◽

pp. 8672

Author(s):

Somnath Chattopadhyaya ◽

Brajeshkumar Kishorilal Dinkar ◽

Alok Kumar Mukhopadhyay ◽

Shubham Sharma ◽

José Machado

Keyword(s):

Sample Size ◽

Reliability Analysis ◽

Small Sample Size ◽

Meta Analysis ◽

Small Sample ◽

Forest Plot ◽

Large Sample Size ◽

Heavy Load ◽

Combining Data ◽

Load Carrier

It is a common recommendation not to attempt a reliability analysis with a small sample size. However, this is feasible after considering certain statistical methods. One such method is meta-analysis, which can be considered to assess the effectiveness of a small sample size by combining data from different studies. The method explores the presence of heterogeneity and the robustness of the fresh large sample size using sensitivity analysis. The present study describes the approach in the reliability estimation of diesel engines and the components of industrial heavy load carrier equipment used in mines for transporting ore. A meta-analysis is carried out on field-based small-sample data for the reliability of different subsystems of the engine. The level of heterogeneity is calculated for each subsystem, which is further verified by constructing a forest plot. The level of heterogeneity was 0 for four subsystems and 2.23% for the air supply subsystem, which is very low. The result of the forest plot shows that all the plotted points mostly lie either on the center line (line of no effect) or very close to it, for all five subsystems. Hence, it was found that the grouping of an extremely small number of failure data is possible. By using this grouped TBF data, reliability analysis could be very easily carried out.

Download Full-text