• Title/Summary/Keyword: biostatistics

Search Result 959, Processing Time 0.026 seconds

A comparison of inverse transform and composition methods of data simulation from the Lindley distribution

  • Okwuokenye, Macaulay;Peace, Karl E.
    • Communications for Statistical Applications and Methods
    • /
    • v.23 no.6
    • /
    • pp.517-529
    • /
    • 2016
  • This study compares the inverse transform and the composition methods for generating data from the Lindley distribution. The expression for the inverse of the distribution function for the Lindley distribution does not exist in closed form. Hence, authors of many empirical studies on the Lindley distribution used methods for generating Lindley variates other than the inverse transform. We generated data from the Lindley distribution using the inverse transform approach by obtaining the Lindley variates numerically; we also generated data from this distribution using the composition approach. Following the generation of the Lindley variates using these two methods, we compare some statistical properties of the estimates of the Lindley model parameters based on the generated data. We conclude that the two methods produce similar results.

Determining the Optimal Cut-off Point According to the Outcome Variables Using R (R을 이용한 결과 변수에 따른 최적의 Cut-off Point 결정)

  • Juyeon Yang;Hye Sun Lee
    • Journal of Digestive Cancer Research
    • /
    • v.10 no.2
    • /
    • pp.99-106
    • /
    • 2022
  • Clinical research ultimately aimed to promptly diagnose and prevent diseases through precise biomarker development. Finding the optimal cut-off point of a regularly measured biomarker can help its interpretation and ultimately help in disease investigation and diagnosis, more specifically in determining the presence of diseases. Therefore, this study aimed to use the characteristics of outcome variables in clinical research to explain how to determine the optimal cutoff point. The outcome variables can be divided into dichotomous, ordinal, and survival types. The optimal cut-off point can be determined by finding points that maximize the Youden index, extended Youden index, and log-rank statistics. This study will enable clinical researchers to accurately determine the optimal cut-off points for regularly measured biomarkers, thereby enabling prompt disease diagnosis for effective treatment.

Prostate Cancer: A Hospital-Based Survival Study from Mumbai, India

  • Balasubramaniam, Ganesh;Talole, Sanjay;Mahantshetty, Umesh;Saoba, Sushama;Shrivastava, Shyam
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.14 no.4
    • /
    • pp.2595-2598
    • /
    • 2013
  • Background: Prostate cancer is common in elderly men, especially in western countries, and incidences are rising in low-risk populations as well. In India, the age-standardized rates vary between registries. Under these circumstances we have estimated the survival of prostate cancer patients based on age, family history, diabetes, hypertension, tobacco habit, clinical extent of disease (risk group) and treatment received. Materials and Methods: The present retrospective study was carried out at the Tata Memorial Hospital (TMH), Mumbai, India. During years 1999-2002, some 850 prostate cancer cases, including 371 new cases, treated in TMH were considered as eligible entrants for the study. Five-year survival rates using actuarial and loss-adjusted (LAR) method were estimated. Results: The patient population was distributed uniformly over the three age groups. A larger proportion of the patients were diagnosed at 'metastatic stage' and hormone treatment was most common. 20% patients had history of diabetes and 40% with hypertension. The 5-year overall survival rate was 64%. Survival was 55%, 74% and 52% for '<59 years','60-69 years' and '>70 years' respectively. Non-diabetic (70%), hypertensive (74%), with family history (80%) of cancer, with localized-disease (91%) and treated with surgery, either alone or in combination, (91%) had better survival. Conclusions: The present study showed that prostate cancer patients with localized disease at diagnosis experience a better outcome. Local treatment with either surgery or radiation achieves a reasonable outcome in prostate cancer patients. A detailed study will help in understanding the prognostic indicators for survival especially with the newer treatment technologies available now.

Evaluation of Related Risk Factors in Number of Musculoskeletal Disorders Among Carpet Weavers in Iran

  • Karimi, Nasim;Moghimbeigi, Abbas;Motamedzade, Majid;Roshanaei, Ghodratollah
    • Safety and Health at Work
    • /
    • v.7 no.4
    • /
    • pp.322-325
    • /
    • 2016
  • Background: Musculoskeletal disorders (MSDs) are a common problem among carpet weavers. This study was undertaken to introduce affecting personal and occupational factors in developing the number of MSDs among carpet weavers. Methods: A cross-sectional study was performed among 862 weavers in seven towns with regard to workhouse location in urban or rural regions. Data were collected by using questionnaires that contain personal, workplace, and information tools and the modified Nordic MSDs questionnaire. Statistical analysis was performed by applying Poisson and negative binomial mixed models using a full Bayesian hierarchical approach. The deviance information criterion was used for comparison between models and model selection. Results: The majority of weavers (72%) were female and carpet weaving was the main job of 85.2% of workers. The negative binomial mixed model with lowest deviance information criterion was selected as the best model. The criteria showed the convergence of chains. Based on 95% Bayesian credible interval, the main job and weaving type variables statistically affected the number of MSDs, but variables age, sex, weaving comb, work experience, and carpet weaving looms were not significant. Conclusion: According to the results of this study, it can be concluded that occupational factors are associated with the number of MSDs developing among carpet weavers. Thus, using standard tools and decreasing hours of work per day can reduce frequency of MSDs among carpet weavers.