| 1. |
- Aires, Nibia
(författare)
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A guide to the Fortran programs to calculate inclusion probabilities for conditional Poisson sampling and Pareto pi ps sampling designs
- 2004
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Ingår i: Computational statistics (Zeitschrift). - Heidelberg : Physica Verlag. - 0943-4062 .- 1613-9658. ; 19:3, s. 337-345
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Tidskriftsartikel (refereegranskat)abstract
- Conditional Poisson Sampling and Pareto pips Sampling designs are sampling methods with fixed sample size and with inclusion probabilities proportional to given size measures.. Algorithms were introduced to calculate first and second exact inclusion probabilities for both schemes. Methods were also provided to adjust the parameters to get predetermined inclusion probabilities. In this paper, the Fortran procedures are introduced and documented. Moreover, guidelines are provided for their use as well as examples and the programs codes commented.
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| 2. |
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| 3. |
- Aires, Nibia, 1959
(författare)
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Techniques to Calculate Exact Inclusion Probabilities for Conditional Poisson Sampling and Pareto .pi.ps Sampling Designs
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of five papers and treats two finite population sampling methods, viz. the Conditional Poisson and the Pareto .pi.ps sampling schemes. Both methods belong to a class of sampling schemes with unequal inclusion probabilities, commonly used in approximate probability to size sampling schemes. Paper A addresses the problem of determining first and second order inclusion probabilities for both methods, which is a vital element in deriving linear estimators. Tools which consist of dynamic programming algorithms, are created to calculate these exact inclusion probabilities. They make it possible to compute the inclusion probabilities in reasonable execution time for small and moderate samples. Algorithms to adjust the parameters so that arbitrary desirable exact inclusion probabilities are achieved are also given. The results in this paper opened the possibility to use the exact Horvitz-Thompson and Yates-Grundy-Sen variance estimators for quite large samples for Conditional Poisson and for moderate samples in the Pareto case. In Paper B, using those algorithms, a computer system was developed to compare and contrast the Conditional Poisson and Pareto .pi.ps sampling designs in terms of estimators of population totals, biases and variances. The computer programme produced an empirical comparison of both methods to check the convergence to the asymptotical inclusions. It also enabled adjustment of the parameters to obtain exact variances and make comparisons in these terms. The results from these studies show that the Pareto scheme approaches asymptotical inclusions faster than the Conditional Poisson, and that both methods are very similar in terms of second order inclusions for the adjusted procedures for moderate samples. The second order inclusion algorithms for the Conditional Poisson Sampling design are generalised in Paper C to a recursive fast procedure to derive higher order inclusion probabilities of arbitrary order. Paper D proves the existence and partial uniqueness of a set of scale parameters when exact inclusion probabilities are required for any order sampling of fixed distribution shape, a class of schemes of which Pareto .pi.ps sampling is a special case. Lastly, Paper E reports on a thorough study of approximation accuracy for Pareto inclusion probabilities, aiming at practical use recommendations, for using asymptotically motivated approximations. Numerical results in this study are presented in Appendix 1 and 2.
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| 4. |
- Berg, Christina, 1963, et al.
(författare)
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Food patterns and cardiovascular disease risk factors: the Swedish INTERGENE research program.
- 2008
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Ingår i: The American journal of clinical nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 88:2, s. 289-97
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Analyzing the impact of the intake of many foods simultaneously provides additional knowledge about analyses of nutrients and might make it easier to implement recommendations for the public. OBJECTIVE: The objective was to examine food patterns in a Swedish population and determine how they are related to metabolic risk factors for cardiovascular disease. DESIGN: The study is based on data from the INTERGENE population study of women and men aged 25-74 y in western Sweden. Dietary patterns were identified with cluster analysis of 93 food frequencies reported by 3452 participants. Associations with features of the metabolic syndrome, including blood lipids, blood pressure, and anthropometric measures, were analyzed. RESULTS: Five distinct food patterns were identified, of which one was interpreted as a "healthy" reference pattern. This healthy cluster was distinguished by more frequent consumption of high-fiber and low-fat foods and lower consumption of products rich in fat and sugar. The 4 other clusters differed significantly from the reference cluster with respect to prevalence of cardiovascular disease risk factors and the metabolic syndrome. For example, body mass index and waist-to-hip ratio were significantly higher in a cluster characterized by high consumption of energy-dense drinks and white bread and low consumption of fruit and vegetables (P < 0.0001 and P = 0.004, respectively). CONCLUSIONS: It is possible to distinguish food patterns that are related to obesity and obesity-related cardiovascular disease risk factors in contrast with a more healthy pattern conforming with current dietary guidelines. Thus, the results indicate no reason for questioning the current recommendations.
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| 5. |
- Berg, Christina, 1963, et al.
(författare)
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Trends in blood lipid levels, blood pressure, alcohol and smoking habits from 1985 to 2002: results from INTERGENE and GOT-MONICA.
- 2005
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Ingår i: European journal of cardiovascular prevention and rehabilitation : official journal of the European Society of Cardiology, Working Groups on Epidemiology & Prevention and Cardiac Rehabilitation and Exercise Physiology. - 1741-8267. ; 12:2, s. 115-25
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Favourable trends in cardiovascular disease have been observed in Sweden. The aim of this study was to study secular trends in a variety of cardiovascular risk factors. METHODS: Total-, low-density (LDL) and high-density lipoprotein (HDL) serum cholesterol; serum triglycerides; systolic and diastolic blood pressure; self-reported smoking and alcohol consumption were studied in repeated cross-sectional surveys. Data from four population-based samples in Goteborg, Sweden were used-WHO MONICA project 1985, 1990 and 1995, and INTERGENE 2002. A total of 2931 females and 2691 males aged 25-64 consisting of 1021-1624 randomly selected subjects at each survey period participated. RESULTS: Serum cholesterol levels showed downward trends but the decline in both total- and LDL-cholesterol seems to be levelling off from 1995 and onwards. No significant changes were observed in serum triglyceride, HDL-serum cholesterol or blood pressure levels. The majority of the participants had higher total- and LDL-serum cholesterol levels than currently recommended. Antihypertensive medical treatment increased in women and the oldest men. The prevalence of smoking decreased from 39 to 25% in women and 35 to 20% in men respectively from 1985-2002. In contrast, the prevalence of subjects consuming strong beer and wine, respectively, at least once a week almost doubled from 1990-2002. CONCLUSIONS: Cardiovascular risk factor patterns change continuously and need to be monitored. The favourable trends in LDL-serum cholesterol and smoking in the Goteborg surveys were paralleled by less favourable trends in being overweight and alcohol consumption.
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| 6. |
- Ekman, Inger, 1952, et al.
(författare)
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Gender makes a difference in the description of dyspnoea in patients with chronic heart failure.
- 2005
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Ingår i: Eur J Cardiovasc Nurs. - : Oxford University Press (OUP). - 1474-5151. ; 4:2, s. 117-21
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dyspnoea is a common symptom of chronic heart failure (CHF). In the community setting, patients with CHF are most often women. Aim: To examine the impact of gender on the description of dyspnoea and to explore which clinical variables support a diagnosis of CHF. Methods: From four primary health care centres, 158 patients with CHF were included. Patients were examined with echocardiography and a cardiologist assessed the diagnosis of CHF. The patients filled in a questionnaire containing 11 descriptors of dyspnoea. Results: A diagnosis of CHF was confirmed in 87 (55%) patients (47 males and 40 females). One descriptor, I feel that I am suffocating, was significantly scored higher in CHF patients ( p=0.014) as compared to non-CHF patients. Three descriptors, My breath does not go in all the way ( p=0.006), I feel that I am suffocating ( p=0.040), and I cannot get enough air ( p=0.0327) were significantly scored higher among men with CHF, compared to no descriptor among women with CHF. Being male (OR=2.7; CI: 1.3–5.6, p=0.008), having diabetes (OR=5.6; CI: 1.7–18.2, p=0.004), IHD (OR=3.3; CI: 1.3–8.5, p=0.014), and a borderline significance for age (OR=1.04; CI: 0.99–1.08, p=0.058) predicted a confirmed diagnosis of CHF. Conclusion: Three descriptors of dyspnoea were associated with CHF among men, whereas no such association was found among women. Our results suggest that gender is an important factor and should—together with age, underlying heart disease, and diabetes—be taken into account when symptoms are evaluated in the diagnosis of CHF in primary care.
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| 7. |
- Strandhagen, Elisabeth, 1960, et al.
(författare)
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The methylenetetrahydrofolate reductase C677T polymorphism is a major determinant of coffee-induced increase of plasma homocysteine: a randomized placebo controlled study.
- 2004
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Ingår i: International journal of molecular medicine. - 1107-3756. ; 13:6, s. 811-5
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Tidskriftsartikel (refereegranskat)abstract
- Some methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms are associated with hyperhomocysteinemia. Trials have shown a plasma homocysteine raising effect of coffee. We determined the effect of a daily intake of 600 ml coffee and a supplementation of 200 microg folic acid or placebo on plasma homocysteine (tHcy) with respect to the MTHFR C677T and A1298C polymorphisms. One hundred and twenty healthy, non-smoking men (22%) and women (78%) aged 29-65 years, took part in a controlled, randomized, blinded study with two intervention periods: i) a coffee-free period of three weeks, ii) 600 ml coffee/day and a supplement of 200 microg folic acid/d or placebo for four weeks. The results showed that tHcy at baseline was significantly higher for the 677TT genotype group compared to the 677CC genotype group (p=0.0045) and that this group responded with significantly larger increase in tHcy upon coffee exposure than the 677CC and 677CT genotype groups (p=0.0045 and p=0.0041, respectively). Supplementation with 200 microg folic acid compared to placebo reduced the tHcy increasing effect of coffee in the 677TT genotype group. The A1298C polymorphism did not affect tHcy concentration significantly at any stage in the study. In conclusion, the homocysteine increasing effect of coffee is particularly seen in individuals with the homozygous 677TT genotype. Supplementation with 200 microg folic acid/d decreases this tHcy increment.
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