The epidemic curve 2 Histogram °Area proportional to number °No space between columns °One population X-axis = time °Start before epidemic, continue after °Interval 1/4 of incubation period Y-axis = number of cases °Usually one square = one case Easy to make in Excel
The semilogaritmic-scale line graph 2 For time series when °interested in rate of change X-axis = time arithmetic Y-axis = rate (or number) of cases, logarithmic °Straight slope= constant rate of change °Steep slope= constant rapid change °Parallell lines= same rate of change °Change in slope = acceleration deceleration of rate °Start at lowest cycle, e.g. 0.1-1 or 1-10 °No breaks
In graphs... Labels for axes, scales and legends Legends or keys if >1 variable Scale divison, appropriate scale Units of measurements in title No grid, no numbers No 3D
Think data-ink Every bit of ink should have a reason
Designing graphics Show the data Use ink for the data Remove unnecessary ink Remove gimmicks No 3D Careful with colours
Standard symbols in tables Avereage BMI by category of weight weightmenwomen 40-49 -. 50-5919,821,8 60-6923,124,8 70-7925,027,6 80-8927,430,5 90-9929,834,2 explanation of symbols - = we measured, no case in this category, we can´t say that it is 0. = we measured, but we cant calculate the average of 1 case
Standard symbols in tables Cause specific mortality Cause of deathmenwomen CVD5035 Pneumonia4530 CA prostatae10x CA cervicis uterix10 explanation of symbols x = not displayed for logical reasons
Summary Use of graphicsExplore and present PresentationPaper vs screen Description °Time- line graphs or epicurves °Place - maps or tables °Person- tables or bar charts °Clinical- tables Analysis °Comparison- 2x2 tables, other tables DesignSave your ink!