Báo cáo y học: " Statistics review 12: Survival analysis" ppt

... 4 The Kaplan–Meier estimates of survival for (a) age > 65 years or ≤ 65 years, and (b) long-term oxygen therapy (LTOT) before intensive care unit admission (yes/no). The P values are for the ... http://ccforum.com/content/8/5/389 Figure 2 Survival curves for the two treatment groups for the data in Table 1. Survival time (days) 80706050403020100 Probability of survival 1.0 0.9 0.8...

Ngày tải lên: 12/08/2014, 20:20

... X 2 ,…, X n ). In other words: Review Statistics review 1: Presenting and summarising data Elise Whitley* and Jonathan Ball † *Lecturer in Medical Statistics, University of Bristol, Bristol, UK † Lecturer ... plots Unordered Ordered Discrete Continuous Ventilatory support Severity of illness Days in ICU Blood pressure Main types: In tables, shown as: Graphically shown as: Types: Exampl...

Ngày tải lên: 12/08/2014, 18:21

... approximately Normal and that the popula- tion SD can be approximated by the sample SD. These assumptions, particularly the first, will generally be valid if the sample is sufficiently large. There may ... generally lie close to the mean, and this is reflected in the tall, narrow distribution. Review Statistics review 2: Samples and populations Elise Whitley* and Jonathan Ball † *Lectur...

Ngày tải lên: 12/08/2014, 18:21

... sufficiently small P value. Similarly, a study with high statistical power will, by definition, make iden- tification of any difference relatively easy, but this can only be achieved in a sufficiently ... apparently null result that shows no difference between groups may simply be due to lack of statistical power, making it extremely unlikely that a true difference will be correctly identifie...

Ngày tải lên: 12/08/2014, 18:21

... subsequent treatment may increase central venous oxygen saturation beyond the level expected by chance. However, the P value in isolation gives no information about the likely size of any effect. As indicated ... early goal-directed therapy may be successful in raising mean arterial pressure by between 9.3 and 18.7 mmHg. As always, it is important to interpret this finding in the context of t...

Ngày tải lên: 12/08/2014, 19:21

... than some hypothesized value, and considers whether this is substantially different from what we would expect by chance. If any observations are exactly equal to the hypothesized value they are ignored ... be Normally distributed, whereas the sign test only requires that they are independent of one another. Alternatively, the dis- crepancy may be a result of the difference in power provided b...

Ngày tải lên: 12/08/2014, 19:21

Ngày tải lên: 12/08/2014, 19:22

Ngày tải lên: 12/08/2014, 19:22

... prospective cohort study conducted by Quasney and coworkers [1] of 402 adults admitted to the Memphis Methodist Healthcare System with community-acquired pneumonia. That study investigated the association ... according to genotype and disease outcome ARDS Genotype Yes No Total CC or CT 11 208 219 TT 1 182 183 Total 12 390 402 Presented are data on outcomes from a study conducted by Quasney an...

Ngày tải lên: 12/08/2014, 20:20

... is binary (e.g. death or survival) , then the probability distribution of the number of deaths in a sample of a particular size, for given values of the explanatory Review Statistics review 14: ... ed. New York, USA: John Wiley and Sons; 2000. 3. Bewick V, Cheek L, Ball J: Statistics review 7: Correlation and regression. Crit Care 2003, 7:451-459. 4. Bewick V, Cheek L, Ball J: Sta...

Ngày tải lên: 12/08/2014, 20:21