Philosophy

The reporting tools used here are based on a number of lessons learned from the intersection of the fields of statistical graphics, graphic design, and cognitive psychology, especially from the work of Bill Cleveland, Ralph McGill, John Tukey, Edward Tufte, and Jacques Bertin.

1. Whenever largely numerical information is displayed, graphs convey the information most often needed much better than tables.
   1. Tables usually show more precision than is warranted by the sample information while hiding important features.
   2. Graphics are much better than tables for seeing patterns and anomalies.
2. The best graphics are ones that make use of features that humans are most accurate in perceiving, namely position along a common scale.
3. Information across multiple data categories is usually easier to judge when the categories are sorted by the numeric quantity underlying the information¹.
4. The most robust and informative descriptive statistics for continuous variables are quantiles and whole distribution summaries².
5. For group comparisons, confidence intervals for individual means, medians, or proportions are not very useful, and whether or not two confidence intervals overlap is not the correct statistical approach for judging the significance of the difference between the two. The half-width of the confidence interval for the difference, when centered at the midpoint of the two estimates, provides a succinct precision display, and this half-interval touches the two estimates if and only if there is no significant difference between the two.
6. Each graphic needs a marker that provides the reader with a sense of exactly what fraction of the sample is being analyzed in that graphic.
7. Tables are best used as backups to graphics.
8. Tables should emphasize estimates that are not functions of the sample size. For categorical variables, proportions have interpretations independent of sample size so they are the featured estimates, and numerators and denominators are subordinate to the proportions. For continuous variables, minimum and maximum, while useful for data quality checking, are not population parameters, and they expand as n↑, so they are not proper summary statistics.
9. With the availability of graphics that over hover text, it is more effective to produce tabular information on demand. The software used here will pop-up tabular information related to the point or group currently pointed to by the mouse. This makes it less necessary to produce separate tables.

Notation

Figure Captions

Needles represent the fraction of observations used in the current analysis. The first needle (red) shows the fraction of enrolled patients used. If randomization was taken into account, a second needle (green) represents the fraction of randomized subjects included in the analysis. When the analyses consider treatment assignment, two more needles may be added to the display, showing, respectively, the fraction of subjects randomized to treatment A used in the analysis and the fraction of subjects on treatment B who were analyzed. The colors of these last two needles are the colors used for the two treatments throughout the report. The following table shows some examples.

# Store using short variable names so Rmarkdown table column
# width will not be wider than actually needed
d1 <- dNeedle(1)
d2 <- dNeedle((3:4)/4)
d3 <- dNeedle((1:2)/4)
d4 <- dNeedle(c(1,2,3,1)/4)

Signpost	Interpretation
	All enrolled subjects analyzed, randomization not considered
	Analysis uses 3⁄4 of enrolled subjects, and all randomized subjects
	Analysis uses 1⁄4 of enrolled subjects, and 1⁄2 of randomized subjects
	Same as previous example, and in addition the analysis utilized treatment assignment, analyzing 3⁄4 of those randomized to A and 1⁄4 of those randomized to B

Introduction

This is a sample of the part of a closed meeting Data Monitoring Committee report that contains software generated results. Components related to efficacy, study design, data monitoring plan,³ summary of previous closed report, interpretation, protocol changes, screening, eligibility, and waiting time until treatment commencement are not included in this example⁴. This report used a random sample of safety data from a randomized clinical trial. Randomization date, dropouts, and compliance variables were simulated, the latter two not being made consistent with the presence or absence of actual data in the random sample. The date and time that the analysis file used here was last updated was2013-10-27 10:50:46. Source analysis files were last updated on primarydatadate.

Accrual

accrualReport(randomize(rdate) ~ site(site), data=base,
              dateRange=c('1990-01-01','1994-12-31'),
              targetDate='1994-12-31', targetN=300,
              closeDate=max(base$rdate))

∟ Participants randomized over time

The blue line depicts the cumulative frequency. The thick grayscale line represent targets.

Category N Used Enrolled 500 250 Randomized 250 250

---

∟ Number of sites × number of participantsrandomized

Number of sites having the given number of participants randomized

Category N Used Enrolled 500 250 Randomized 250 250

---

Baseline Variables

# Simulate regions
set.seed(1)
base$region <- sample(c('north', 'south'), nrow(base), replace=TRUE)
dReport(sex + race + smoking ~ region + trx, groups='trx', data=addMarginal(base, region))

∟ Proportions for sex, race, and smoking stratified by region and treatment

Proportions for sex, race, and smoking stratified by region and treatment. N=250

Category N Used Enrolled 500 250 Randomized 250 250 A 81 81 B 169 169

Variable A B Sex 81 169 Race 81 169 Smoking 81 169

## Show spike histogram and quantiles for raw data
dReport(age + height + weight + bmi + pack.yrs ~ trx, data=base,
        popts=list(ncols=2))

---

∟ Histograms for age, height, weight, BMI, and pack years stratified by treatment

Histograms for age, height, weight, BMI, and pack years stratified by treatment. N=250

Category N Used Enrolled 500 250 Randomized 250 250 A 81 81 B 169 169

Variable A B Age 81 169 Height 81 169 Weight 81 169 BMI 81 169 Pack Years 81 169

Longitudinal Adverse Events

dReport(headache + ab.pain + nausea + dyspepsia + diarrhea +
        upper.resp.infect + coad ~ week + trx + id(id),
        groups='trx', data=ssafety, what='byx',
        popts=list(ncols=2, height=700, width=1100))

∟ Means and 0.95 bootstrap percentile confidence limits for 7 variables vs. week stratified by treatment

Means and 0.95 bootstrap percentile confidence limits for 7 variables vs. week stratified by treatment. N=250

Category N Used Enrolled 500 250 Randomized 250 250 A 81 81 B 169 169

Variable A B headache 81 169 abdominal pain 81 169 nausea 81 169 dyspepsia 81 169 diarrhea 81 169 upper resp tract infection 81 169 chronic obstructive airways disease 81 169