Large Positive Correlation Research Articles

Chemical properties, microbial biomass, and activity differ between soils of organic and conventional horticultural systems under greenhouse and open field management: a case study

Increasing soil organic matter content is important in improving soil fertility; however, conventional farming practices generally lead to a reduction in such organic material. A comparative study of organic and conventional arable farming systems was conducted in Shanghai, China, to determine the influence of management practices on soil chemistry, microbial activity, and biomass. Soils used in greenhouses and open field cultivation were obtained from plots subjected to organic farming methods for 3 years or from conventionally farmed fields in the same area. Four combinations of field type and management system were evaluated: (1) organic management in open fields (ORG-OP); (2) conventional management in open fields (CNV-OP); (3) organic management in plastic tunnel fields (ORG-GR); and (4) conventional management in plastic tunnel fields (CNV-GR). Soils obtained at the 0- to 10-cm depth were analyzed using an approach combining traditional soil analysis, microbiological analysis using enzymology and microcalorimetric techniques, and a written survey of management practices among the farmers. Organic management resulted in significant increases (p < 0.001) in total organic C and total N, Olsen-P, cation exchange capacity (CEC), soil respiration, microbial biomass C (C min) and N (N min), and alkaline phosphatase and urease activity. Sucrase activity was highest in CNV-GR soil and lowest in ORG-OP and CNV-OP soils. No significant difference was observed between ORG-OP and CNV-OP. The Olsen-P, total organic C, total N, CEC, N min, and sucrase and alkaline phosphatase activities were greater in greenhouse soils than those under open field cultivation, which indicated a higher level of soil management under greenhouse conditions. The microcalorimetry power–time curves for all samples described typical microbial metabolic activity. In soil samples supplemented with glucose and ammonium sulfate, the heat dissipation per cell unit suggested that microorganisms in soils under organic management had more efficient metabolism. In addition, microbial growth in soils under conventional management displayed lower growth rates, lower peak heat, and longer peak heat times, all of which indicated lower activity of soil microorganisms compared with organic management. There was a large positive correlation (p < 0.01) between the values of P max (the peak value of thermal power), Q total (total heat flux), and k (microbial growth rate constant) and the chemical properties. However, there was a significant negative correlation (p < 0.05) between the value of t max (the time required to reach peak thermal power) and chemical properties other than sucrase activity. Organic production systems significantly improved soil microbial characteristics and increased soil organic C, thus improving soil quality and fertility. Further studies investigating the long-term functional significance of carbon sequestration under organic practices are therefore warranted.

Performance analysis of demand planning approaches for aggregating, forecasting and disaggregating interrelated demands

A synchronized and responsive flow of materials, information, funds, processes and services is the goal of supply chain planning. Demand planning, which is the very first step of supply chain planning, determines the effectiveness of manufacturing and logistic operations in the chain. Propagation and magnification of the uncertainty of demand signals through the supply chain, referred to as the bullwhip effect, is the major cause of ineffective operation plans. Therefore, a flexible and robust supply chain forecasting system is necessary for industrial planners to quickly respond to the volatile demand. Appropriate demand aggregation and statistical forecasting approaches are known to be effective in managing the demand variability. This paper uses the bivariate VAR(1) time series model as a study vehicle to investigate the effects of aggregating, forecasting and disaggregating two interrelated demands. Through theoretical development and systematic analysis, guidelines are provided to select proper demand planning approaches. A very important finding of this research is that disaggregation of a forecasted aggregated demand should be employed when the aggregated demand is very predictable through its positive autocorrelation. Moreover, the large positive correlation between demands can enhance the predictability and thus result in more accurate forecasts when statistical forecasting methods are used.

Establishing validity evidence for the Sport Multidimensional Perfectionism Scale-2 in intercollegiate sport

Objectives The purpose of the two studies presented in this paper is to establish validity evidence for the Sport Multidimensional Perfectionism Scale-2 (Sport-MPS-2: Gotwals & Dunn, 2009). Studies 1 and 2 are respectively focused on the production of structurally-related and external validity evidence. Methods In Study 1, 263 male and female intercollegiate volleyball players ( M age = 19.98 years) completed the Sport-MPS-2. In Study 2, 181 male intercollegiate ice hockey players ( M age = 22.16 years) responded to the Sport-MPS-2, the Multidimensional Perfectionism Scale ( Frost, Marten, Lahart, & Rosenblate, 1990), and a modified Sport Anxiety Scale ( Smith, Smoll, & Schutz, 1990). Results Exploratory factor analysis results in Study 1 revealed supportive structurally-related validity evidence for the six factors of the Sport-MPS-2. Study 2 generated supportive external validity evidence by producing anticipated moderate to large positive correlations between conceptually analogous Sport-MPS-2 and Frost-MPS subscales (all ps < .001), using canonical correlation to demonstrate that the Sport-MPS-2 was able to represent theory-based relationships between perfectionism and competitive trait anxiety (CTA), and indicating that the Sport-MPS-2—but not the Frost-MPS—was capable of identifying an anticipated link between healthy perfectionism and CTA. Conclusions Results provide support for the continued use of the Sport-MPS-2 as a measure of multidimensional perfectionism in sport.

Relationships amongst age, language and related skills in adults with Down syndrome

Studies into the effects of ageing on language in adults with Down syndrome (DS) have tended to rely on measures that lack sensitivity to change because they fail to explore across linguistic domains or rely on proxy reports. The study aim was to use measures of receptive and expressive language from studies of younger individuals with DS in exploring relationships across linguistic and associated skills, and age in young to older adults. Fifty-five adults (aged 19–58 years), 10 with a diagnosis of or signs of early stage Alzheimer's Disease (AD), provided data on measures of functioning associated with AD, non-verbal cognition, receptive language (which provided a measure of mental age), receptive and expressive language, and short term auditory and visual memory. The first order correlation between the measure of AD and CA was significant; but not when the 10 participants with AD were removed from the analysis. Significant negative correlations were obtained between CA and all other measures; small to large significant positive correlations were found amongst the other measures. Partial correlations were conducted to remove the potential effects of AD and IQ (the latter measured by a test of non-verbal cognition). Remaining significant correlations were between auditory short term memory and all other included measures, expressive language and all other included measures, and CA and auditory short term memory and expressive language. The results indicate that deterioration with age in this cross-sectional study was accounted for largely by the presence of AD. The exceptions were for auditory short term memory and expressive language. The findings may reflect an underlying deficit in auditory short term memory for adults with DS, as has been found in previous research of children and adolescents. The implications are discussed in terms of the importance of including comprehensive measures of receptive and expressive language and the need to account for the presence of AD in studies of cognitive decline associated with ageing in DS.

Performances Of The Full Information Estimators In A Two-Equation Structural Model With Correlated Disturbances

The performances of two full information techniques, Three Stage Least Squares (3SLS) and Full Information Maximum Likelihood (FIML) of simultaneous equation models with correlated disturbance terms are compared with the Ordinary Least Squares (OLS) method in small samples. Comparative performance evaluation of the estimators was done using Average of Estimates, Total Absolute Bias (TAB) of Estimates, Root Mean Squared Error (RMSE) and Sum of Squared Residuals (RSS) of parameter estimates. The results of the Monte Carlo experiment showed that OLS is best with large negative or positive correlation, while 3SLS is best with feebly correlated error terms in the case of replication-based averages. The total absolute biases increase consistently as the sample size increases for OLSwhile FIML estimates reveal no distinct pattern. The magnitudes of the estimates yielded by two estimators, OLS and 3SLS, exhibited fairly consistent reaction to changes in magnitudes and direction of correlations of error terms.

The evaluation of scientific productivity in Brazil: An assessment of the mental health field

Brazilian scientific production has increased significantly over the last decade, and mental health has been a leading research field in the country, with a growing number of articles published in high quality international journals. This article analyses the scientific output of mental health research between 2004 and 2006 and estimates individual research performance based on four different strategies. A total of 106 mental health scientists were included in the analysis; together they published 1,209 articles indexed in Medline or ISI, with over 65% of the production in journals with impact factor ≥1. Median impact factor of publications was 2. Spearman correlation coefficient showed a large positive correlation between all four different measures used to estimate individual research output. Ten investigators were together responsible for almost 30% of the articles published in the period, whereas 65% of the sample contributed with less than 10 articles.

Fit of Wood's function to daily milk records and estimation of environmental and additive and non-additive genetic effects on lactation curve and lactation parameters of crossbred dual purpose cattle

The objectives of this study were to estimate the environmental and additive and non-additive genetic effects on lactation curve and lactation parameters of crosses of Holstein (H), Brahman (B) and Brown Swiss (BS) in Olancho region in Honduras. The data consisted of 54,517 milk yield records from 192 dual-purpose crossbred cows lactating from 2000 to 2005 at the Universidad Nacional de Agricultura de Honduras (UNA). The lactation curve and lactation parameters of interest were the scaling factor to represent yield at the beginning of lactation ( a), the factor associated with the inclining ( b) and declining ( c) slopes of the lactation curves, and the milk yield at initial day of lactation ( MY 20), peak milk yield ( MY max), day at peak milk yield ( t max), and the total milk yield ( TM) per lactation, respectively. The incomplete gamma function (Wood function) was used to estimate lactation curve and lactation parameters from daily milk records of H × B, H × BS and BS × B crossbred cows. The environmental, additive and non-additive genetic effects on lactation curve and lactation parameters were estimated using Dickerson and Kinghorn models. The coefficients of determination of fitness of Wood's function ( R 2) ranged from 80% to 97% with an average of 93%. The lactation curve of the crossbred cows was similar to those reported for dairy cows grazing in the tropics. Lactation parameters such as MY max, t max and TM were significantly ( P < 0.05) influenced by environmental sources of variation suggesting the necessity of differential management strategies. The moderate to large positive phenotypic correlation of MY max and TM indicate that one of the milk yield parameters could be used as a selection criterion to improve either one or both traits. Despite the fact that both genetic models showed similar patterns, the absolute value of the parameters varied. For both models, individual additive genetic breed effect for H breed were significant ( P < 0.05) and contributed more to TM than the BS breed. In the Dickerson model, highly positive significant ( P < 0.01) effect on TM for H×BS and BS×B crosses was found. The Kinghorn model did not show significant effects of dominance on this parameter. The estimate of recombination effect for all crosses involving B breed were negative and significant ( P < 0.05) for positive correlated lactation curve parameters. Although the inclusion of non-additive effects on crossbreeding genetic effects were not all significant for lactation curve and lactation parameters, non-additive effects should be taken into account to improve the Honduran dairy cattle production management.

Witness confidence and accuracy: is a positive relationship maintained for recall under interview conditions?

AbstractA large positive correlation between eyewitness recall confidence and accuracy (C‐A) is found in research when item difficulty is varied to include easy questions. However, these results are based on questionnaire responses. In real interviews, the social nature of the interview may influence C‐A relationships, and it is the interviewer's perception of the accuracy of a witness that counts. This study was conducted to investigate the influence of these factors for recall of a video. Three conditions were used; the same questions were used in each. Participants in condition 1 (self‐rate questionnaire condition, n = 20) were given a questionnaire that required them to answer questions and rate confidence on a scale. Pairs of participants in condition 2 (self‐rate interview condition, n = 40) were given the role of eyewitness or interviewer. Eyewitnesses were asked questions by an interviewer and responded orally with answers and confidence judgements on a Likert scale. Participants in condition three (interviewer‐rate interview condition, n = 40) were tested in the same way as condition two but provided confidence judgements in their own words. Interviewers independently rated each confidence judgement on the Likert scale. The experiment showed high C‐A relationships, particularly for ‘absolutely sure’ responses. The main effect of the social interview condition was to increase confidence in correct answers but not in incorrect answers. However, the advantage of this effect was tempered by the fact that, although observers can differentiate between confident and less confident answers, less extreme confidence judgements were ascribed. Copyright © 2009 John Wiley &amp; Sons, Ltd.

The representations of spacing and part-based information are associated for upright faces but dissociated for objects: Evidence from individual differences

Considerable evidence suggests that qualitatively different processes are involved in the perception of faces and objects. According to a central hypothesis, the extraction of information about the spacing among face parts (e.g., eyes and mouth) is a primary function of face processing mechanisms that is dissociated from the extraction of information about the shape of these parts. Here, we used an individual-differences approach to test whether the shape of face parts and the spacing among them are indeed processed by dissociated mechanisms. To determine whether the pattern of findings that we reveal is unique for upright faces, we also presented similarly manipulated nonface stimuli. Subjects discriminated upright or inverted faces or houses that differed in parts or spacing. Only upright faces yielded a large positive correlation across subjects between performance on the spacing and part discrimination tasks. We found no such correlation for inverted faces or houses. Our findings suggest that face parts and spacing are processed by associated mechanisms, whereas the parts and spacing of nonface objects are processed by distinct mechanisms. These results may be consistent with the idea that faces are special, in that they are processed as nondecomposable wholes.

Crude Substitution: The Cyclical Dynamics of Oil Prices and the Skill Premium

Higher oil-price shocks benefit unskilled workers relative to skilled workers: At the business-cycle frequency, energy prices and the skill premia display a strong, negative correlation. We assess the robustness of this negative correlation using several methods and data sources, including sector-level data. We find that the negative correlation is robust to different de-trending procedures, and the wages of unskilled workers in energy-intensive industries have a larger positive correlation with oil prices. We also estimate the parameters of an aggregate technology, which uses, among other inputs, energy and heterogeneous skills. We find that both capital-skill and capital-energy complementarity are responsible for this correlation pattern. As energy prices rise, the use of capital decreases and the demand for unskilled labor relative to skilled labor increases, resulting in lower skill premia.

MV-optimal block designs for correlated errors

Abstract This paper presents M V -optimal block designs for three treatments having b = 3 n + 1 blocks each of size three when observations within each block are correlated. Two distinct covariance structures are considered, and the optimality problem is addressed using generalized least squares estimation of treatment contrasts in fixed-block effects model. In particular, it is shown that a design d ∗ having n copies of the blocks (1, 2, 3), (2, 3, 1), (3, 1, 2) and one copy of (1, 3, 2) is M V -optimal within the class of all equally replicated connected designs. A class of unequally replicated designs is found to be M V -better than d ∗ in the unrestricted class of all connected designs for large positive correlations.

The reliability analysis of a thin-edge blade wear in the glass fiber cutting process

This study shows that the reliability analysis of a thin-edge blade plays an important role in cutting glass fiber and explores the main effect of three cutting factors: the cutting speed, the cutting load, and the cutting volume. The effect of each cutting factor on the thin-edge blade wear, as determined by long glass fiber weight, and exceeding a value of 1%, as specified in the customer's requirements, was investigated. According to the experimental results, the thin-edge blade wear distribution approximated to a Weibull distribution, and the cumulative probability could be determined after nine iterations. This study also finds that there is a large positive correlation among the various thin-edge blade-wear values at different cutting speeds. However, the correlation is negative for the various thin-edge blade-wear values when cutting at load, and when cutting at different cutting volumes. It was observed also that the optimum cutting speed with minimum thin-edge blade wear is 1.9 m/s. The successful deployment of this study will be a significant factor in improving the cutting process and cutting quality.

Searching for epistasis and linkage heterogeneity by correlations of pedigree‐specific linkage scores

Recognizing that multiple genes are likely responsible for common complex traits, statistical methods are needed to rapidly screen for either interacting genes or locus heterogeneity in genetic linkage data. To achieve this, some investigators have proposed examining the correlation of pedigree linkage scores between pairs of chromosomal regions, because large positive correlations suggest interacting loci and large negative correlations suggest locus heterogeneity (Cox et al. [1999]; Maclean et al. [1993]). However, the statistical significance of these extreme correlations has been difficult to determine due to the autocorrelation of linkage scores along chromosomes. In this study, we provide novel solutions to this problem by using results from random field theory, combined with simulations to determine the null correlation for syntenic loci. Simulations illustrate that our new methods control the Type-I error rates, so that one can avoid the extremely conservative Bonferroni correction, as well as the extremely time-consuming permutational method to compute P-values for non-syntenic loci. Application of these methods to prostate cancer linkage studies illustrates interpretation of results and provides insights into the impact of marker information content on the resulting statistical correlations, and ultimately the asymptotic P-values.

A preliminary study of the relationship between Australian wine consumers' wine expertise and their wine purchasing and consumption behaviour

Few Australian wine companies have the resources to acquire consumer relevant information to assist their strategic decision-making. This exploratory study examined the relationship between Australian consumers' wine expertise and their self-reported wine related behaviours, such as wine purchasing and consumption. A measure of consumer wine expertise developed specifically for the Australian consumer, comprising a wine knowledge test and an aroma identification (sensory) test, was used to segment 61 wine consumers into three expertise levels. A large positive correlation between wine expertise and formal wine training was demonstrated. Data showed that females dominated the low and males the high expertise groups, respectively. The high expertise level consumers spent more on wine, purchased more bottles and fewer casks per month and consumed more wine in a week than the low and medium expertise groups. Analysis revealed significant differences between the styles of wine consumed by the various expertise levels. A combination of Factor and Cluster analyses generated three distinct consumer segment profiles based on wine purchase drivers. These preliminary data indicate that wine consumers' wine behaviour may be influenced by their wine expertise.

Biometrics of the mussel Anodonta cygnea (L.) inhabiting in 2005 the Binowo and Bobolin Lakes near Szczecin

Abstract Research on the swan mussel population was conducted in 2005 on a sample of 497 individuals inhabiting Binowo and Bobolin Lakes, Szczecin, Poland. Length, width, height and age of individuals was examined. Binowo Lake was inhabited by individuals aged 1+ to 7+ years, while individuals aged 1+ to 6+ inhabit Bobolin Lake. Measurable features of swan mussels inhabiting Binowo Lake were as follows: individuals were 3.80 to 10.20 cm long, 1.70 to 5.70 cm wide, 0.70 to 3.70 cm thick, and in Bobolin Lake, 4.00 to 15.20 cm long, 2.20 to 7.70 cm wide, 0.80 to 5.70 cm thick. The age structure of both populations included individuals of diverse ages, with 3 and 4-year old individuals dominating in both lakes. A modest fraction of the youngest individuals (1, 2-year old) as well as the oldest (6, 7-year old) was observed in the examined lakes. All correlations between shell length, width, height and mussel age showed large positive correlations and results obtained from both lakes were similar.

Relations between the Thermal and Mechanical Properties of Cast Zr-TM-Al (TM: Cu, Ni, or Co) Bulk Glassy Alloys

Ternary Zr-TM-Al (TM: Cu, Ni or Co) bulk glassy alloys were fabricated to clarify the relations between the thermal and mechanical features. These alloy systems show the distinct ternary eutectic point, and a bulk glassy phase also forms around the ternary eutectic composition. We determine the 12 standard Zr-TM-Al bulk glassy alloys in this study. In the twelve standard Zr-TM-Al bulk glassy alloys, the glass-transition temperature has large positive correlation coefficient with Young's modulus and Vickers hardness. The melting temperature has large negative correlation coefficient with Charpy impact value, fracture strain and volume change due to structural relaxation. Furthermore, in order to recognize the origin of ductility, Poisson's ratio (metallic bond nature) and volume change (free volume) were also examined.

A first comparison of irregularity and ion drift velocity measurements in the E-region

Abstract. E-region irregularity velocity measurements at large flow angles with the STARE Finland coherent VHF radar are considered in context of the ion and electron velocity data provided by the EISCAT tristatic radar system, CUTLASS Finland coherent HF radar, and IMAGE fluxgate magnetometers. The data have been collected during a special experiment on 27 March 2004 during which EISCAT was scanning between several E- and one F-region altitudes along the magnetic field line. Within the E-region, the EISCAT measurements at two altitudes of 110 and 115 km are considered while the electron velocity is inferred from the EISCAT ion velocity measurements at 278 km. The line-of-sight (l-o-s) VHF velocity measured by STARE VHF los is compared to the ion and electron velocity components (Vi0 comp and Ve0 comp) along the STARE l-o-s direction. The comparison with Ve0 comp for the entire event shows that the measurements exhibit large scatter and small positive correlation. The correlation with Ve0 comp was substantial in the first half of the interval under study when Ve0 comp was larger in magnitude. The comparison with Vi0 comp at 110 and 115 km shows a considerable positive correlation, with VHF velocity being typically larger (smaller) in magnitude than Vi0 comp at 110 km (115 km) so that VVHF los appears to be bounded by the ion velocity components at two altitudes. It is also demonstrated that the difference between VVHF los and Vi0 comp at 110 km can be treated, in the first approximation, as a linear function of the effective backscatter height heff also counted from 110 km; heff varies in the range 108–114 km due to the altitude integration effects in the scattering cross-section. Our results are consistent with the notion that VHF velocity at large flow angles is directly related to the ion drift velocity component at an altitude heff.

Using the theory of planned behavior to understand the determinants of exercise intention in patients diagnosed with primary brain cancer

The purpose of the present study was to examine the demographic, medical, and social cognitive determinants of exercise intentions in a institution-based cohort of primary brain tumor patients. Using a cross-sectional survey, 100 primary brain tumor patients completed a mailed survey that assessed medical and demographic characteristics, past exercise behavior using the Godin Leisure Time Exercise Questionnaire (GLTEQ), and social cognitive beliefs towards exercise using Aizen's theory of planned behavior (TPB; i.e. intention, perceived behavioral control, subjective norm, affective and instrumental attitude). Descriptive statistics indicated that participants had positive social cognitive beliefs towards exercise. In support of the tenets of the TPB, we found moderate to large (>0.40) positive correlations between the majority of TPB constructs. Moreover, the TPB constructs combined to explain 32% of the variance in exercise intentions with affective attitude (beta = 0.24; p = 0.020) and perceived behavioral control (beta = 0.36; p<0.001) being the most important determinants. Except past exercise behavior, medical and demographic variables were not consistently correlated with any TPB constructs. Finally, participant's gender and body mass index influenced the association between instrumental attitude and exercise intention with male and overweight/obese patients (> or =25 kg/m(2)) considering the health benefits of exercise to be more important than their female and normal weight (<25 kg/m(2)) counterparts. Information gained from this study suggests that the TPB is a useful framework to design and implement theoretically based interventions to promote exercise in primary brain cancer patients.

High-Frequency Variability in Hurricane Power Dissipation and Its Relationship to Global Temperature

The power dissipation of Atlantic tropical cyclones has risen dramatically during the last decades and the increase is correlated with an increase in the underlying sea surface temperature (SST) at low (decadal) frequencies. Because of the large positive correlation between global mean surface air temperature (GT) and Atlantic SST it has been speculated that increases in the power dissipation might, in part, be related to human activity. Here we investigate the question of the relationship between GT and hurricane power dissipation directly using statistical analysis and show that after removing the effect of SST, the correlation between GT and hurricane power dissipation is negative. This suggests that the positive influence of global temperature on Atlantic hurricanes appears to be limited to an indirect connection with tropical Atlantic SST. We also show that the relationship between hurricane power dissipation and Atlantic SST is significant at the high-frequency time scales. El Niño–Southern Oscillation (ENSO) plays an important role in statistically explaining the variations in hurricane power at these higher frequencies.

Birth Weight and Blood Pressure in Spouses

ArticlePlus Click on the links below to access all the ArticlePlus for this article. Please note that ArticlePlus files may launch a viewer application outside of your web browser. https://links.lww.com/EDE/A215 To the Editor: Low birth weight is correlated with high adult blood pressure according to the programming hypothesis,1–3 but the estimated effect is small4 and may even be confounded by social conditions or lifestyle factors.3,5 We studied the association between birth weight and blood pressure in couples to adjust for the social conditions that couples share. We randomly selected 1000 cohabiting couples, 50 to 65 years of age, from the Danish cohort study Diet, Cancer and Health. Using the place and date of birth, and names as identifiers, we located each person's birth record in the state archive; these midwife records include data on birth weight. If we could not match by one surname (maiden name) and place of birth for both partners, the couple was excluded from further analysis. We extracted data on midlife systolic and diastolic blood pressure (SBP and DBP) from the health examination at recruitment to the cohort study. Data were analyzed in a mixed model of 2 linear regression equations allowing for dependence between measurements from spouses.6 Analyzing husband and wife jointly allows for adjustment for latent lifestyle factors. We located 1670 of the 2000 individuals with birth data (84%). The midwife records of the 330 remaining persons were either missing or too ambiguous for identification. Among the 1670 persons with midwife data, both partners' data were available in 472 couples. Table 1 shows the slope estimates of SBP and DBP on birth weight from several models. The confounder adjustment for both latent and fixed lifestyle covariates did not substantially change the effect of birth weight on SBP and DBP. Inclusion of current body mass index in the analyses also did not affect estimates.7,8TABLE 1: Effect of Birth Weight (per kilogram)Furthermore, we found an unexpected, relatively large positive correlation between the blood pressure of one spouse and the birth weight of the other. According to the data, a man with low birth weight will experience high SBP as seen in Figure 1. At the same time, his high SBP correlates with both high birth weight and high SBP of the wife. That is difficult to explain in causal terms. This unexpected pattern was present but less apparent for DBP.FIGURE 1.: Correlations of birth weight and systolic blood pressure in the couple. The P values refer to statistical significance of the hypothesis of no correlation.These estimated associations could be the result of chance. Otherwise, we speculate whether selection of spouses or effect modification by lifestyle or treatment of high blood pressure is at work. We recommend that other spouse data are used to see whether our findings can be replicated. The proportion of couples with missing birth data either for one or both partners was large but most likely unrelated to the hypothesis under study. Data were missing when midwife records were simply lost in the archive and for persons born on a day when a midwife had more than one delivery of mothers with the same surname. None of these conditions should cause selection bias, except by chance. Birth weight and outcome data were collected independently, which makes differential misclassification unlikely. Our objective was to put the programming hypothesis on birth weight and adult blood pressure to a critical test. We got results that corroborate the association, but the finding of a correlation between the blood pressure of one spouse and the birth weight of the other may also serve as a warning sign. One should be careful when interpreting results from 2 measurements made 50 years apart without much control of what took place in the time between. For more details regarding this study, refer to the supplementary material available with the online version of this letter. ACKNOWLEDGMENTS We thank Hanne Grand for patiently reading the midwife protocols. Thanks are also due to Anne Tjønneland and the staff at the Danish study Diet, Health and Cancer. Anne Vingaard Olesen Institute of Public Health Department of Epidemiology University of Aarhus Aarhus, Denmark [email protected] Erik Thorlund Parner Institute of Public Health Department of Biostatistics University of Aarhus Aarhus, Denmark Kim Overvad Department of Clinical Epidemiology Aarhus University Hospital Aarhus, Denmark Jørn Olsen The Danish Epidemiology Science Centre at the Institute of Public Health University of Aarhus Aarhus, Denmark UCLA School of Public Health Department of Epidemiology Los Angeles, California