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本文目的是介绍简单线性回归分析的前提条件、 种类、 实现计算的 S A S程序及结果解释, 并说明数据是否值得做直线回归分析以及如何选择正确的直线回归分析类型.简单线性回归分析有三种具体情形, 分别是 简单直线回归分析、加权直线回归分析和具有重复试验的直线回归分析.进一步通过实例来阐述如何进行不同的简单线性回归分析, 并给出实现这些直线回归分析所需要的 S A S程序及输出结果.

目的探讨住院时fu3长短对精神分裂症患者出院时的自知力影响。方法在广州市脑科医院连续人组且符合《国际疾病分类（第10版）》（ICD-10）精神分裂症诊断标准的住院患者265例，采用阳性和阴性症状量表（PANSS）、自知力和治疗态度问卷（ITAQ）分别测评患者的精神症状和自知力。采用相关性分析及线性回归分析探索自知力和治疗态度的影响因素。结果本组患者住院天数中位数为61（35～97）天，出院时ITAQ评分（11．1±5．8）分。PANSS各分量表、总评分及住院天数与ITAQ评分均有相关性（P〈0．05）。线性回归分析显示PANSS阳性症状、阴性症状和住院1年以上是自知力的危险因素（B=-0．403，-0．232，-2．979，P〈0．05），住院天数对ITAQ的解释度仅为1．9％。结论患者出院时的自知力主要受精神症状影响，住院时间长短对自知力的影响不大，适度缩短精神分裂症患者住院天数对自知力恢复可能不会产生负面影响。

本文目的是介绍基于经典统计思想实现多重线性回归分析的方法。首先,概述基于经典统计思想、贝叶斯统计思想和机器学习统计思想建立多重线性回归模型的基本思路;然后以实际问题为例,全面呈现了多重线性回归分析所需要完成的主要任务;最后,总结多重线性回归分析的适用场合及注意事项。结果表明：产生派生变量、进行自变量筛选和共线性诊断、进行异常点诊断等内容是进行多重线性回归分析的主要任务。在多因素试验或观察性研究中,只要结果变量为计量变量,比较常用且有效的做法是进行多重线性回归分析,应尽可能少用单因素差异性分析。

Background： Recent studies show that microRNA- 145 （miRNA- 145 ） might be an attractive tumor biomarker of considerable prognostic value, but little is known about their relationship with acute myocardial infarction （AMI）. This study investigated the correlation between the level of miR-145 and AM1. Methods： One-hundred patients were divided into three groups： no coronary artery disease （CAD） group, non-ST segment elevation myocardial infarction group, and ST segment elevation myocardial infarction group. The plasma levels of miR-145 were quantified using real-time quantitative polymerase chain reaction. Logarithmic transformation of miRNA-145 levels （Ln_rniRNA-145） was used for statistical analysis due to the skewed data distribution. Results： Plasma levels of miR-145 were significantly lower in patients with AMI compared to patients in the non-CAD group （-6.38 ± 0.11 vs. -4.47 ＋ 0.17, P 〈 0.0001）. Compared to those without heart failure, the levels of miR-145 were significantly lower in patients with heart failure （-6.91 ± 0.20 vs. -5.35 ± 0.13, P 〈 0.0001）. We also found that the lower plasma levels of miRNA-145 significantly correlated with increased serum levels of B-type natriuretic peptide （Spearman ρ = -0.60, P 〈 0.0001）, troponin T （Spearman p = -0.62, P 〈 0.0001）, and decreased ejection fraction （Spearman ρ = 0.65, P 〈 0.0001）. In a multivariable linear regression analysis, AMI and heart failure were independently associated with lower Ln miRNA-145 （estimate -0.99, standard error [SE] 0.28; P = 0.001 and estimate -0.62, SE 0.21 ; P = 0.004）. Conclusions： Our results suggest that decreased plasma levels of miR-145 are associated with AMI. Circulating miR-145 may be useful in prognosticating cardiac function and the risk of developing heart failure.

Soil depth generally varies in mountainous regions in rather complex ways. Conventional soil survey methods for evaluating the soil depth in mountainous and hilly regions require a lot of time, effort and consequently relatively large budget to perform. This study was conducted to explore the relationships between soil depth and topographic attributes in a hilly region in western Iran. For this, one hundred sampling points were selected using randomly stratified methodology, and considering all geomorphic surfaces including summit, shoulder, backslope, footslope and toeslope; and soil depth was actually measured. Eleven primary and secondary topographic attributes were derived from the digital elevation model (DEM) at the study area. The result of multiple linear regression indicated that slope, wetness index, catchment area and sediment transport index, which were included in the model, could explain about 76 % of total variability in soil depth at the selected site. This proposed approach may be applicable to other hilly regions in the semi-arid areas at a larger scale.

In this study, we aim to improve the scaling between the moment magnitude （Mw）, local magnitude （ME）, and the duration magnitude （MD） for 162 earthquakes in Shillong-Mikir plateau and its adjoining region of northeast India by extending the Mw estimates to lower magnitude earthquakes using spectral analysis of P-waves from vertical component seismograms. The Mw-ML and Mw-MD relationships are determined by linear regression analysis. It is found that, Mw values can be considered consistent with ME and My, within 0.1 and 0.2 magnitude units respectively, in 90 % of the cases. The scaling relationships investigated comply well with similar relationships in other regions in the world and in other seismogenic areas in the northeast India region.

Background： Facioscapulohumeral muscular dystrophy （FSHD）, a common autosomal dominant muscular disorder, is caused by contraction of the D4Z4 repeats on 4q35. The complicated genotype-phenotype correlation among different ethnic population remains a controversial subject. We aimed to refine this correlation in order to provide new information for genetic counseling. Methods： Here, a cohort of[36 Chinese families including 178 affected individuals and 137 unaffected members were investigated. Genetic analyses were pertbrmed using the pl 3E-11, 4qA and 4qB probes after pulsed field gel electrophoresis separation and southern blotting. A I 0-grade FSHD clinical severity scale was adopted for clinical assessment. The genotype-phenotype correlation was established by linear regression analyses. Results： We observed a roughly inversed correlation between the short EcoRl fragment size and age-corrected clinical severity score in 154 symptomatic patients （P 〈 0.05）. Compared to male patients, a significant higher proportion of females in both asymptomatic carriers and severe patients showed larger variation in the size of short EcoRI fragment. A high incidence （ 19/42, 45.2%） ofasymptomatic （or minimally affected） carriers was found in familial members. Conclusions： Although the number of D4Z4 repeats is known as one of the critical influences on genotype-phenotype correlation, a rnajority ofphenotypic spectrum was still incompatible with their heterozygous contraction of the D4Z4 repeat, especial in female cases. Our resuhs suggest that there are multi-factors synergistically modulating the phenotypic expression.

Background： Both Parkinson＇s disease （PD） and multiple system atrophy （MSA） have associated sleep disorders related to the underlying neurodegenerative pathology. Clinically, MSA with predominant parkinsonism （MSA-P） resembles PD in the manifestation of prominent parkinsonism, Whether the amount of rapid eye movement （REM） sleep without atonia could be a potential marker for differentiating MSA-P from PD has not been thoroughly investigated. This study aimed to examine whether sleep parameters could provide a method for differentiating MSA-P from PD. Methods： This study comprised 24 MSA-P patients and 30 PD patients, and they were of similar age, gender, and REM sleep behavior disorder （RBD） prevalence. All patients underwent clinical evaluation and one night of video-polysomnography recording. The tonic and phasic chin electromyogram （EMG） activity was manually quantified during REM sleep of each patient. We divided both groups in terms of whether they had RBD to make subgroup analysis. Results： No significant difference between MSA-P group and PD group had been tbund in clinical characteristics and sleep architecture. However, MSA-P patients had higher apnea-hypopnea index （AHI; 1.15 [0.00, 8.73]/h vs. 0.00 [0.00, 0.55]/h, P = 0.024） and higher tonic chin EMG density （34.02 [ 18.48, 57.18]% vs. 8.40 [3.11, 13.061%, P 〈 0.001 ） as compared to PD patients. Subgroup analysis found that tonic EMG density in MSA ＋ RBD subgroup was higher than that in PD ＋ RBD subgroup （55.04 [26.81,69.62]% vs. 11.40 [8.51,20.411%, P 〈 0.001 ）. Furthermore, no evidence of any difference in tonic EMG density emerged between PD ＋ RBD and MSA - RBD subgroups （P 〉 0.05）. Both disease duration （P = 0.056） and AHI （P = 0.051） showed no significant differences during subgroup analysis although there was a trend toward longer disease duration in PD ＋ RBD subgroup and higher AHI in MSA - RBD subgroup. Stepwise multiple linear regression analysis identified the presence of MSA-P （[3 0.552, P 〈 0.001 ） and RBD （[3 = 0.433, P 〈 0.001 ） as predictors of higher tonic EMG density. Conclusion： Tonic chin EMG density could be a potential marker for differentiating MSA-P from PD.

During underground coal gasification （UCG）, whereby coal is converted to syngas in situ, a cavity is formed in the coal seam. The cavity growth rate （CGR） or the moving rate of the gasification face is affected by controllable （operation pressure, gasification time, geometry of UCG panel） and uncontrollable （coal seam properties） factors. The CGR is usually predicted by mathematical models and laboratory experiments, which are time consuming, cumbersome and expensive. In this paper, a new simple model for CGR is developed using non-linear regression analysis, based on data from 1 l UCG field trials. The empirical model compares satisfactorily with Perkins model and can reliably predict CGR.

Based on eddy covariance measurements over two kinds of land surfaces（a degraded grassland and a maize cropland） in a semiarid area of China in 2005 and 2008, the effects of different gap filling methods, energy balance closure and friction velocity threshold（u＊） on annual net ecosystem exchange（NEE） were analyzed. Six gap filling methods, including mean diurnal variation（MDV）, marginal distribution sampling（MDS）, and nonlinear regressions method, were investigated by generating secondary datasets with four different artificial gap lengths（ranging in length from single half-hours to 12 consecutive days）. The MDS generally showed a good overall performance especially for long gaps, with an annual sum bias error less than 5 g C m-2 yr-1. There was a large positive annual sum bias error for nonlinear regressions, indicating an overestimate on net ecosystem respiration. The offset in the annual sum NEE for four nonlinear regressions was from 8.0 to 30.8 g C m-2 yr-1. As soil water content was a limiting factor in the semiarid area, the nonlinear regressions considering both soil temperature and soil water content as controlling variables had a better performance than others. The performance of MDV was better in daytime than in nighttime, with an annual sum bias error falling between-2.6 and-13.4 g C m-2 yr-1. Overall, the accuracy of the gap filling method was dependent on the type of the land surface, gap length, and the time of day when the data gap occurred. The energy balance ratio for the two ecosystems was nearly 80%. Turbulent intensity had a large impact on energy balance ratio. Low energy balance ratio was observed under low friction velocity during the night. When there was a large fetch distance in a wind direction, a low energy balance ratio was caused by mismatch of the footprints between the available energy and turbulent fluxes. The effect of energy balance correction on CO2 flux was evaluated by assuming the imbalance caused by the underestimation of sensible heat flux and latent heat flux. The results showed an average increase of 10 g C m-2 yr-1 for annual NEE in both ecosystems with an energy balance correction. On the other hand, the u＊ threshold also have a large impact on annual sum NEE. Net carbon emission increased 37.5 g C m-2 yr-1 as u＊ threshold increased from 0.1 to 0.2 m s-1, indicating a large impact of imposing u＊ threshold on net ecosystem carbon exchange.