Báo cáo y học: " Statistics review 6: Nonparametric methods" docx
Báo cáo y học: " Statistics review 6: Nonparametric methods" docx
... risk less than 1.0 (a ‘negative’
Review
Statistics review 6: Nonparametric methods
Elise Whitley
1
and Jonathan Ball
2
1
Lecturer in Medical Statistics, University of Bristol, Bristol, UK
2
Lecturer ... 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 va...
Báo cáo y học: "Statistics review 1: Presenting and summarising data" pptx
... 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...
Báo cáo y học: "Statistics review 2: Samples and populations" potx
... 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...
Báo cáo y học: "Statistics review 4: Sample size calculations" doc
... 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...
Báo cáo y học: "Statistics review 5: Comparison of means" docx
... 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...
Báo cáo y học: " Statistics review 11: Assessing risk" doc
... community-acquired pneumonia. Crit
Care Med 2004, 32:1115-1119.
2. Whitley E, Ball J: Statistics review 2: Samples and populations.
Crit Care 2002, 6:1 43-148
3. Bewick V, Cheek L., Ball J: Statistics ... viable in this type of
study, but RR is generally easier to interpret.
The AR indicates that 14.4% of the successful outcomes can
be directly attributed to the early goal-directed the...
Báo cáo y học: " Statistics review 12: Survival analysis" ppt
... 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 log rank test.
391
test the null hypothesis that ... bronchiectasis
Explanatory 95% confidence
variables Risk ratio interval P
Age (>65 years) 2.7 1.15–6.29 0.022
LTOT (yes) 3.12 1.47–6.90 0.003
LTOT, long-term oxygen therapy.
... time, the
star...
Báo cáo y học: "Statistics review 14: Logistic regression" doc
... 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: Statistics review ... 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
Statistic...