... M.D., Ph.D. http://home.kku.ac.th/sompong1
STATISTICSBASIC CONCEPTS
DESCRIPTIVE STATISTICSINFERENTIAL STATISTICS
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http://home.kku.ac.th/sompong
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Scales of measurement Distribution, Central tendency Variability, Probability Prevalence, Incidence Disease outcomes
Fatality rates Confidence intervals Association
Pearson chi-square, Fishers exact test 4 P-value
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(2550)
5
.
SMJ 2550; 22: 254-60.
http://www.smj.ejnal.com/e-journal/showdetail/?show_detail=T&art_id=1261
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15 1. 2. 3. 4. 5. 6.
()
)
)
)
)
1
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35-45
28-34
0-27
1
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2
= + () =
outcome = unhappiness
(unhappiness)
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% (, ) (. 4, 5, 6) (, ) (, , , ) 1 , , ,
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%
Pearson chi-square Fishers exact test
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Mean standard deviation Median interquartile range
() GPA (Grade Point Average) () () ()
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T-test Mann-Whitney U test
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N % OR 95% CI P-value
-
-
159
254
17.0
5.5
3.51
1.00
1.70, 7.31
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(SPSS)
Happiness vs. Gender
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()
N % OR 95% CI P-value
- -
335
78
8.4
16.7
0.46
1.00
0.21, 0.99
0.027 *
- -
301
112
8.6
13.4
0.61
1.00
0.30, 1.27
0.151 *
* Pearson chi-square
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()
N % OR 95% CI P-value
-
-
-
-
-
340
18
37
18
7.9
22.2
24.3
5.6
1.00
3.31
3.73
0.68
1.02, 10.76
1.60, 8.70
0.09 , 5.32
0.006*
* Fishers exact test
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()
N % OR 95% CI P-value
- -
40
373
17.5
9.1
2.11
1.00
0.79, 5.48
0.098 *
- -
64
349
42.2
4.0
17.46
1.00
7.97, 38.73
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()
N % OR 95% CI P-value
-
-
121
292
27.3
2.7
13.31
1.00
5.63, 32.56
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()
N % OR 95% CI P-value
- -
82
331
12.2
9.4
1.34
1.00
0.59, 3.02
0.443 *
* Pearson chi-square
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()
P-value
-
Median (IQR)
- Min, Max
16.0 (1.0)
15.0,
19.0
17.0 (1.0)
14.0, 19.0
0.070 *
GPA
-
Median (IQR)
- Min, Max
2.98
(0.81)
1.75,
3.77
3.26
(0.68)
1.24,
4.00
0.027
*
* Mann-Whitney U test
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()
P-value (hr/wk)
-
Median (IQR)
- Min, Max
3.0
(10.0)
0.0,
32.0
4.0
(8.0)
0.0, 26.0
0.605
*
(hr)
-
Median (IQR)
- Min, Max
7.0 (1.0)
4.0, 9.0
7.0 (2.0)
3.0, 11.0
0.457
*
* Mann-Whitney U test
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()
P-value (hr)
-
Median (IQR)
-
Min, Max
8.0, 3.0
4.0, 12.0
8.0 (2.0)
0, 14
0.468
* Mann-Whitney U test
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ERROR: TYPE I, II
Type II
Type I
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CONFOUNDING FACTOR MODIFYING FACTOR
AND INTERACTION
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27 37
14 335
16 18
11 114
11 19
3 221
+ - + -
+ -+-
+-
+-
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Odds ratio 95% CI
Adjusted odds ratio
(95%
CI)
17.46 7.97,
38.7315.77
(9.67,
29.24) 9.21 3.38,
25.57
42.65 42.65,
249.33
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RISK FACTOR PROTECTIVE FACTOR
VS. PROMOTIVE FACTOR
OBSTRUCTIVE FACTOR
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RR OR RR (OR) > 1
Bad outcome: Good outcome:
RR (OR) < 1 Bad outcome: Good outcome:
RR (OR) =1 outcome
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MULTIPLE LOGISTIC REGRESSION
TO DETERMINERISK / PROTECTIVE FACTOR
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8. POTENTIAL SIGNIFICANT FACTORS (P-value 0.250) P-value
FACTOR P-VALUE1.2.3.4.5.6.7.8.9.
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MODEL
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RISK DIFFERENCE
attributable risk absolute risk Risk1 Risk2
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27 37
14 335
+ -+-
41
372
413
64
349
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RISK REDUCTION
Relative risk reduction RR, OR intervention study 1
Absolute risk reduction risk difference intervention study Control event rate
Experiment event rate number needed to treat
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NUMBER NEEDED TO TREAT
one additional bad outcome
1 / absolute risk reduction
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NUMBER NEEDED TO HARM
1
1 / risk difference
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CORRELATION
vs.
statistical significance
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PEARSON CORRELATION
Correlations
1 -.154**.003
364 362-.154** 1.003362 410
Pearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)N
GPA
Student's income
GPAStudent'sincome
Correlation is significant at the 0.01 level (2-tailed).**.
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SPEARMAN CORREALTION KENDALL TAU CORRELATION
Correlations
1.000 -.126**. .003
364 362-.126** 1.000.003 .362 410
1.000 -.154**. .003
364 362-.154** 1.000.003 .362 410
Correlation CoefficientSig. (2-tailed)NCorrelation CoefficientSig. (2-tailed)NCorrelation CoefficientSig. (2-tailed)NCorrelation CoefficientSig. (2-tailed)N
GPA
Student's income
GPA
Student's income
Kendall's tau_b
Spearman's rho
GPAStudent'sincome
Correlation is significant at the 0.01 level (2-tailed).**.
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STATISTICS 15 % % Slide Number 12 () () () () () () () ()ERROR: TYPE I, IICONFOUNDING FACTOR MODIFYING FACTOR ANDINTERACTIONRISK FACTORPROTECTIVE FACTORVS.PROMOTIVE FACTOROBSTRUCTIVE FACTOR RR ORMULTIPLELOGISTIC REGRESSION8. POTENTIAL SIGNIFICANT FACTORS(P-value 0.250) P-value MODEL RISK DIFFERENCERISK REDUCTIONNUMBER NEEDED TO TREATNUMBER NEEDED TO HARMCORRELATIONPEARSON CORRELATIONSPEARMAN CORREALTIONKENDALL TAU CORRELATION
