SLIDE 1

Descriptive StudyAya Goto

Key concepts

Nicely presented quantitative data tells a lot WITHOUT p-values.

Graphs and tables

SLIDE 2

Grades of evidence

SLIDE 3

Concato J, Shah N, Horwitz RI. Randomized, controlled trials, observational studies, and the hierarchy of research designs.N Engl J Med. 2000 Jun 22;342(25):1887-92.

This is where research starts!

Descriptive and Analytical study

Descriptive study: Describe distribution of each factor individually.

Analytical study: Analyze associations among factors.

In any study design, you must describe distribution of all factors you investigate.

This is the very basic and most important of all study designs.

SLIDE 4

SLIDE 5

Abortion trends in Japan, 1975-95. Goto A, Fujiyama-Koriyama C, et al. Stud Fam Plann. 2000; 31(4): 301-8.

0

10

20

30

40

<2020-2425-2930-3435-3940-44

1980 1985 1990 1995

Abortion rate (per 1000 women)

SLIDE 6

100

1000

10000

<2020-2425-2930-3435-3940-44

1980 199519901985

Abortion ratio (per 1000 live births)

SLIDE 7

N(%)

Infections Nghi Thuy

Nghi Khanh

Nghi Thuan

Nghi Xa

Hung Thong

(N = 46) (N = 35) (N = 47) (N = 36) (N = 44)Any infection 19 (41.3) 14 (40.0) 14 (29.8) 14 (38.9) 20 (45.5)Endogenous infectionsCandidiasis 5 (10.9) 6 (17.1) 8 (17.0) 8 (22.2) 12 (27.3)Bacterial vaginosis 2 ( 4.4) 4 (11.4) 4 ( 8.5) 2 ( 5.6) 3 ( 6.8)Group B streptococcus 3 ( 6.5) 1 ( 2.9) 3 ( 6.4) 3 ( 8.3) 1 ( 2.7)STDTrichomoniasis 2 ( 4.4) 0 ( 0.0) 0 ( 0.0) 0 ( 0.0) 0 ( 0.0)Gonorrhea 0 ( 0.0) 0 ( 0.0) 0 ( 0.0) 0 ( 0.0) 1 ( 2.7)Syphilis 0 ( 0.0) 0 ( 0.0) 0 ( 0.0) 0 ( 0.0) 0 ( 0.0)Hepatitis B 12 (26.1) 4 (11.4) 2 ( 4.3) 2 ( 5.6) 4 ( 9.1)

Prevalence of and factors associated with reproductive tract infections among pregnant women in ten communes in Nghe An Province, Vietnam.

Goto A, Nguyen QV, et al. J Epidemiol. 2005; 15(5): 163-72.

SLIDE 8

Ecologic fallacy

Is protein causing colon cancer?

Table and figure format

SLIDE 9

TableTable 1. Age-specific abortion rates and ratios in Japan and Fukushima, 2000

Age groupTotal <20 20-24 25-29 30-34 35-39 40-44 45-49

Abortion rate (per 1000 women)Japan 11.6 12.2 20.1 15.1 14.2 13.2 6.2 0.5Fukushima 20.7 18.4 30.8 23.8 22.9 19.9 10.2 0.7

Abortion ratio (per 1000 live births)Japan 285 2249 512 154 156 420 1624 5775Fukushima 390 2627 462 203 237 607 2324 13500

SLIDE 10

Bar chart

0.02.04.06.08.0

10.012.014.016.0

1995 1996 1997 1998 1999 2000 2001

Abortion rate (1000 women)

Figure 1. Trends in abortion rate, Japan, 1995-2001

SLIDE 11

Line graph

0

5

10

15

20

25

1980-84 1985-89 1990-94 1995-99

FukushimaJapan

Abortion rate （ 1000 women ）

Figure 2. Trends in abortion rate, Japan and Fukushima, 1980-1999

SLIDE 12

HistogramFigure 3. Age-specific proportion of abortion cases, Japan, 1999

05

1015

2025

Per

cent

1 2 3 4 5 6var1 <20 20-24 25-29 30-34 35-39 40-44

SLIDE 13

USAGETable Precise dataBar chart TrendLine graph Trend

(Comparing several groups)

Histogram Distribution

Summary measures

SLIDE 14

Table 1. Basic characteristics of pregnant womenN (%) or Median (min, max)

Age (years) 27 (18, 44)Occupation

Housewife 27 ( 5.4) Agriculture 317 (62.8) Business 62 (12.3) Government employee 71 (14.1) Others 28 ( 5.5)Education

None to primary school 64 (12.7) Secondary school 271 (53.7) High school 101 (20.0) Professional school 53 (10.5) University 15 ( 3.0)Household assets (0-6)* 3 (1, 6)

* Electricity, bicycle, motorbike, running water, television, and telephone were the assets measured.

SLIDE 15

Arithmetic rules can NOT be applied. N (%)• Categorical data

Blood type: 1= O, 2=A, 3=B, and 4=ABInjury: 1=fatal, 2=severe, 3=moderate, 4=minor

Arithmetic rules can be applied. Summary measures• Continuous data

Hb level Number of births that woman has given.

SLIDE 16

Summary measures of continuous dataMean=average

Standard Deviation(SD)

Mean±2SDs = a range in which “most” of your subjects fit. (About 95% lie within 2 SDs)

Median=50th percentile

Range=Min/MaxMode=most frequent value(s)

SLIDE 17

Age: 6, 6, 7, 8, and 25Mean =Median =Mode =

SLIDE 18

Selection of Measures1. Sample size: Large (>30) --> Mean (SD)

Small --> Median (Min,Max)

2. Shape

Bell-shape Mean(= Median = Mode)

More than one peaks Mode

Skewed to the right (left) Median

Median/ModeMean

Clinical descriptive epidemiologyModel case from a private clinic in JP

Shironishi Clinic Dr. Ogawa, Yutaka General practitioner in a remote area

Practice Diary

(Year / Month / Day) No. Out-patients ( ) No. Home visits ( )

ID NAME TEL NO. TREATMENT

Other Notes

Check points

Daily practice notes

Date ID Name Birth date

Referral hospital

Reason Follow-up response #1

#2 #3

Referral notes

SLIDE 23

Total Follow-up response received No responseTotal Brief visit

record onlyTreatment record

Total Satisfactory Not satisfactory

268 (100%)

221 (82%)

36 (13%)

185 (69%)

157 (59%)

28 (10%)

47 (18%)

“A systematic referral system should be established.” A referral card was introduced in the region. The paper was awarded.

Kosei No Sihyo2000: 47(8): 23-28.

Simple clinical-oriented descriptive study

SLIDE 24

Better

practice