Hemostasis in Open Acetabulum and Pelvic Ring Surgery Using Tranexamic Acid: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hemostasis in Open Acetabulum and Pelvic Ring Surgery Using Tranexamic Acid (NCT02051686), a randomized na study. The primary outcome is Intra-operative Blood Loss.

2. Clinical Question

The clinical question is framed as a comparison between assigned groups, not as a test of whether TXA is beneficial in every individual. The posted primary results describe average blood loss and its variability in each group, alongside an estimated between-group mean difference and a confidence interval. The secondary transfusion outcome provides another view of perioperative blood use, but it is not interchangeable with measured blood loss: one records a volume, while the other records whether a participant required a transfusion. The registry summary gives a study purpose involving safety and cost efficiency, but the posted outcomes do not report a cost-efficiency result. The clinical importance threshold for blood loss or transfusion is not reported in the registry record.

3. Trial Design

The registry describes a prospective, randomized, controlled study with a double mask and a parallel design. The study compared TXA with placebo in patients undergoing open surgery for acetabulum and pelvic ring injuries. The registry lists enrollment as 88. The posted primary outcome group sizes are 42 for TXA and 46 for placebo; these are the group sizes attached to the reported endpoint, not a statement about the number analyzed for every outcome.

The TXA group was assigned a 10 mg/kg loading dose approximately 15 minutes before surgical start time, followed by a 1 mg/kg/h infusion over 10 hours. The placebo group received a similar volume load of normal saline and maintenance doses. The registry lists University of Missouri-Columbia as sponsor. The study began in 2013-06, primary completion was 2016-12, and the status is completed.

The registry identifies the primary endpoint as mean intra-operative blood loss in milliliters on the day of surgery. It also lists the number of participants requiring an allogeneic transfusion during the perioperative hospitalized period as a secondary outcome. The record gives no reported analyses for that secondary outcome. The specific randomization procedure, allocation concealment approach, masking roles, eligibility criteria, center count, and handling of protocol deviations are not reported in the registry record. The original design assumptions for sample size and the detailed statistical analysis plan are also not reported in the registry record.

Randomization is intended, in general, to create groups that are comparable on average at the start of a study; masking is intended, in general, to reduce the influence of knowledge of assignment on care or assessment. Those general purposes do not establish how well these procedures were implemented in this trial. The registry identifies the design features but does not provide enough detail to assess their implementation.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Intra-operative Blood Loss, measured over Day of Surgery.

The primary endpoint is intra-operative blood loss, recorded in milliliters on the day of surgery. The posted results summarize this continuous measurement by its mean and standard deviation for each group. The mean describes the group average, while the standard deviation describes how spread out individual measurements are around that average. These summaries address the amount of blood loss during the operation, rather than total blood loss across the full hospital stay or blood loss after surgery.

Blood loss is used as an outcome because it directly quantifies bleeding during the procedure and permits a comparison of average measured volume between randomized groups. It is distinct from a transfusion outcome: transfusion depends on whether blood was given and is counted as a participant-level event, whereas blood loss is a measured volume. The registry lists transfusion separately as a secondary outcome.

In the posted primary results, mean blood loss was 727.6 milliliters in the TXA group and 560.1 milliliters in the placebo group. The estimated mean difference, defined as TXA minus placebo, was 167.5 milliliters. The confidence interval ranges from -71.45 to 406.5 milliliters. This estimate describes the direction and uncertainty of the observed group contrast; it does not by itself establish a clinically important difference. A threshold for clinical importance, the measurement procedure, and information about missing endpoint values are not reported in the registry record.

7. Results Posted in the Registry

• Tranexamic Acid: mean 727.60 versus 560.10 on control; difference 167.50 (95% CI -71.45 to 406.45), standardized effect d = 0.30; z-test p = 0.169.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Number of Participants That Required an Allogenic Transfusion

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Tranexamic Acid: 50.0% (21/42) versus 32.6% (15/46) on control; risk difference 17.4 percentage points (95% CI -2.9 to 37.7), risk ratio 1.53 (0.92–2.56); unadjusted two-proportion z-test p = 0.097.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tranexamic Acid and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists one secondary endpoint: the number of participants requiring an allogeneic transfusion during the perioperative hospitalized period. The posted group counts are 21 in the TXA group and 15 in the placebo group. The unadjusted comparison has a risk difference of 0.174, a confidence interval from -0.029 to 0.377, and an unadjusted p-value of 0.097. These results are uncertain: the interval includes no difference as well as contrasts in either direction.

This secondary outcome concerns whether a transfusion occurred, not the volume of blood lost during the operation. It can complement the primary endpoint by describing a related aspect of perioperative blood use, but it does not reproduce or validate the continuous blood-loss measurement. The primary estimate also has a confidence interval spanning zero. Taken together, the posted results do not give a clear, precise separation between groups on either endpoint; they should be interpreted as uncertain estimates rather than as definitive support for a particular effect.

The registry lists no reported analyses for the transfusion endpoint. Its displayed comparison is unadjusted, and the registry does not say whether adjustment for other factors or for multiple outcomes was planned or performed. In general, testing multiple outcomes or contrasts can increase the chance that at least one result appears noteworthy by chance. Without a reported multiplicity plan, secondary findings usually carry less evidential weight than a prespecified primary result, especially when the analysis and its priority are unclear.

The registry does not report additional secondary outcome results beyond this listed endpoint. It also does not give a hierarchy of secondary questions or identify a confirmatory role for the transfusion comparison. The secondary result is therefore best treated as supporting context, not as an independent confirmation of the primary result or as a substitute for the missing details of the statistical plan.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Number of Participants That Required an Allogenic Transfusion

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is continuous: blood loss is recorded as a volume, and the registry reports group means and standard deviations. The main contrast is a mean difference, with the estimate expressed as TXA minus placebo. A positive value therefore corresponds to a higher observed mean in the TXA group; a negative value corresponds to a lower observed mean in the TXA group. The posted estimate is 167.5 milliliters.

What does a mean difference summarize?

In general, a mean difference compares the average outcome in one group with the average in another. It is expressed in the outcome's original units, so a difference in milliliters retains a direct connection to measured blood volume. This contrast does not describe every participant's experience and can be affected by variability and unusual observations. The group means and standard deviations are useful summaries, but they do not reveal the full distributions.

How should the standard deviations be read?

The standard deviation describes the spread of participant measurements around a group mean. The reported values are 702.5 milliliters for TXA and 378.4 milliliters for placebo. In general, greater variability can make an estimate of a group mean, and especially a between-group difference, less precise. Unequal spreads can also matter when choosing or assessing a statistical method. The registry does not report diagnostic checks or enough detail to establish whether the analysis accounted for unequal variability.

The comparison includes a confidence interval from -71.45 to 406.5 milliliters. In general, a confidence interval is a range of estimates compatible with the observed data under the method's assumptions. It conveys uncertainty about the mean difference and its possible direction and size. It is not a range containing every participant's blood loss, and it is not the probability that the true value lies in the interval. The interval crosses zero, which is the value corresponding to no mean difference.

What does the p-value contribute?

The unadjusted p-value for the primary contrast is 0.169. In general, a p-value describes how unusual data at least as extreme as those observed would be under a specified null model and the assumptions of the test. It is not the probability that the null hypothesis is true, and it does not measure the clinical importance of an estimate. A p-value alone does not convey the range of effects compatible with the results, so it should be read alongside the estimate and confidence interval.

The secondary transfusion endpoint is binary at the participant level: a participant either required an allogeneic transfusion during the stated period or did not. The registry reports counts by group, a risk difference, confidence interval, and unadjusted p-value. In general, a risk difference compares the proportions experiencing an event in two groups, expressed as a difference in risks. It is distinct from the continuous mean difference for blood loss. The reported risk-difference estimate is 0.174, its interval ranges from -0.029 to 0.377, and the unadjusted p-value is 0.097. The registry also gives ratio measures, but the interpretation of any such measure depends on its scale and uncertainty; these secondary comparisons remain unadjusted.

Why can over-dispersion matter?

In general, over-dispersion means that outcome variation is greater than a model assumes. When a model understates variation, standard errors can be too small and confidence intervals can be too narrow. The blood-loss summaries show appreciable variability, but the registry does not report a fitted model, residual checks, or a finding of over-dispersion. It would therefore be inappropriate to claim that a particular adjustment was needed or used. This is a general statistical consideration, not a reported feature of the trial analysis.

The registry identifies the trial as randomized and double-masked, but does not report the detailed primary analysis method, covariate adjustment, missing-data method, or population used for analysis. It also does not report a multiplicity procedure. The displayed comparisons should therefore be understood as unadjusted summaries and contrasts rather than as evidence of a particular prespecified model. The registry reports no analyses for the secondary transfusion outcome. There is not enough information in the record to determine whether the posted endpoint counts include every randomized participant, how unavailable measurements were handled, or whether any sensitivity analyses were conducted.

The planning illustrations use the observed effect as a reference and show scenarios based on specified fractions of that effect. In general, such calculations translate an assumed effect and design assumptions into a prospective sample-size requirement. They do not retrospectively establish the probability that this completed study would detect an effect. The original trial's sample-size justification and design assumptions are not reported in the registry record.

11. Confidence Intervals and Precision

Precision concerns how narrowly the data estimate the group contrast. For intra-operative blood loss, the estimated mean difference is 167.5 milliliters and its confidence interval ranges from -71.45 to 406.5 milliliters. This interval is wide enough to include a negative contrast, no difference, and positive contrasts. Consequently, the results do not identify the direction or magnitude of the underlying mean difference with high precision.

In general, a confidence interval describes uncertainty around an estimate under the method used to construct it. The interval is not a prediction of the range of individual blood-loss measurements and does not mean that every value inside it is equally plausible. Nor does its crossing zero establish equivalence. To support equivalence, the study would need a prespecified margin and an analysis designed to assess that question; such a margin is not reported in the registry record.

The posted standard deviations are 702.5 milliliters for TXA and 378.4 milliliters for placebo, indicating substantial spread in the observed measurements. The group sizes attached to the primary outcome are 42 and 46. Variability and sample size both bear on precision in general, but the registry does not report the original sample-size assumptions or the analysis method in enough detail to reconstruct a full assessment of precision.

For transfusion, the risk-difference estimate is 0.174 and its interval ranges from -0.029 to 0.377. This interval also includes no difference and spans values in either direction. The two outcomes therefore both have uncertainty that should remain central to interpretation. The registry does not report clinically important thresholds for either endpoint, so statistical uncertainty cannot be translated into a threshold-based judgment about clinical importance.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are prospective illustrations, not observed study outcomes. For these non-time-to-event outcomes, the entries are participants per arm, not a total across arms or a total number of events. The assumptions listed for the illustrations are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is defined as the stated fraction of the observed effect. The trial's own original sample-size assumptions are not reported in the registry record.

For the primary blood-loss outcome, planning for 100% of the observed effect gives 174 participants per arm for 80% power and 233 participants per arm for 90% power. Planning for 75% of the observed effect gives 309 participants per arm for 80% power and 414 participants per arm for 90% power. Planning for 50% of the observed effect gives 695 participants per arm for 80% power and 930 participants per arm for 90% power.

For the transfusion outcome, planning for 100% of the observed effect gives 125 participants per arm for 80% power and 167 participants per arm for 90% power. Planning for 75% of the observed effect gives 219 participants per arm for 80% power and 293 participants per arm for 90% power. Planning for 50% of the observed effect gives 483 participants per arm for 80% power and 646 participants per arm for 90% power.

In plain terms, 80% power is a planning target for the chance of detecting the assumed effect under the stated assumptions; the 90% column uses a higher target and consequently requires more participants per arm. Smaller effects need more participants to detect than larger effects, as the rows illustrate. These are planning calculations, not observed power.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 167.500; pooled standard deviation σ = 556.968.
2. n = 2 × (1.96 + 0.842)² × 556.968² / 167.500² = 173.6, rounded up to 174 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 167.5                      # observed difference in means
sigma <- 556.967532417682                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2051686)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 174 (80% power), 233 (90% power)
 75% of observed effect: n per arm = 309 (80% power), 414 (90% power)
 50% of observed effect: n per arm = 695 (80% power), 930 (90% power)
power.t.test: 174.5 
Simulated power at n = 174 per arm: 0.796 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when several outcomes, comparisons, subgroups, or analysis choices are examined. In general, the more opportunities there are to find a result that appears unusual, the more important it is to prespecify priorities or use an appropriate adjustment. The registry lists intra-operative blood loss as the primary outcome and identifies transfusion as a secondary outcome. It does not report whether a formal testing hierarchy or multiplicity adjustment was planned or applied. The original statistical analysis plan is not reported in the registry record.

The primary comparison is accompanied by an unadjusted p-value of 0.169, and the secondary transfusion comparison by an unadjusted p-value of 0.097. These values do not account for any multiplicity unless the analysis method explicitly does so; no such method is reported. The secondary result should therefore be interpreted cautiously and should not be elevated to a confirmatory finding on the basis of its p-value alone. The registry reports no formal analyses for the secondary endpoint.

Missing-data handling is also not reported in the registry record. The reported outcome group sizes are 42 for TXA and 46 for placebo, but the record does not state whether all randomized participants had an evaluable blood-loss measurement or whether the endpoint-specific groups differ from the randomized groups. It does not describe imputation, exclusions, withdrawals, or sensitivity analyses for missing observations. The registry enrollment is 88, but the record does not provide a participant flow detailed enough to connect enrollment, assignment, follow-up, and analysis for every outcome.

Analysis populations are not defined in the posted record. In general, an intention-to-treat analysis retains participants in their randomized groups, while other analysis populations may use different eligibility or adherence rules. The registry does not say which population was used, how crossovers or protocol deviations were handled, or whether more than one analysis population was examined. It would be inappropriate to assume a particular approach. These omissions limit reproducibility and make it harder to assess whether the posted group comparisons fully preserve the randomized design.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: venous thromboembolism (2.4%).

The adverse-event record lists serious events among 42 participants at risk in the TXA group and 46 at risk in the placebo group. It records 1 serious event for TXA and 0 for placebo. The most frequently listed serious-event term is venous thromboembolism, reported as 2.4%. The record shows 0 other adverse events in each group and 0 deaths in each group.

These figures describe events recorded in the registry; they do not establish that an event was caused by the assigned treatment. A difference in event counts can be difficult to interpret when counts are small, and the record does not provide enough detail about event timing, adjudication, severity grading, or causal assessment. The term listing does not by itself establish the full clinical course of an event or whether it was considered treatment-related.

The adverse-event figures should be read as a limited safety description, not as proof that a treatment is safe or unsafe. The registry does not report a detailed safety analysis or a prespecified method for comparing adverse events. Nor does the absence of a recorded event in a group establish that no such event could occur outside the observations recorded for this trial.

16. What the Result Does, and Does Not, Mean

The posted results estimate a higher average intra-operative blood loss in the TXA group than in the placebo group, with a mean difference of 167.5 milliliters. The confidence interval ranges from -71.45 to 406.5 milliliters, so the estimate remains compatible with contrasts in either direction as well as no mean difference. The unadjusted p-value is 0.169. The data therefore do not provide a precise answer about the direction or size of the average difference.

The transfusion comparison is also uncertain. Its unadjusted estimate and confidence interval include no difference, and the registry reports no formal analyses for this secondary outcome. These findings are not evidence of equivalence: the registry does not provide an equivalence margin or a non-inferiority design. They also do not establish that TXA increases or decreases blood loss or transfusion in other settings.

The results do not answer every question raised by the study purpose. The record describes an interest in safety and cost efficiency, but the posted outcomes do not report a cost-efficiency analysis. The adverse-event listing is limited and does not establish causation. No clinical-importance threshold is reported for blood loss or transfusion, so the numerical contrasts cannot be categorized against such a threshold.

Interpretation is further limited by the absence of reported details about endpoint missingness, analysis populations, the original statistical analysis plan, and multiplicity handling. Those details matter because they help establish exactly which participants and methods underpin the estimates. The registry identifies the study as randomized and double-masked, but it does not report enough implementation detail to assess those features fully.

The appropriate conclusion is bounded: the posted group summaries and comparisons describe the observed data and their uncertainty in this trial. They do not prove that the assignments have identical effects, and they do not support a firm claim about a clinically important benefit or harm. Broader claims about other patients, procedures, dosing approaches, or settings are not established by this registry record.

17. Why This Trial Matters Statistically

This trial is statistically informative because it illustrates the difference between an estimated effect and the certainty of that estimate. The primary contrast is expressed in milliliters, which makes its direction and scale interpretable, but the confidence interval is broad and crosses zero. Reading the estimate without its interval could make the observed difference seem more conclusive than the data support.

The blood-loss endpoint also demonstrates why averages should be read alongside variability. The standard deviations are 702.5 milliliters for TXA and 378.4 milliliters for placebo. In general, a mean can conceal a wide spread of individual observations, and substantial variation affects precision. The registry does not provide individual-level distributions or diagnostic information, so the summaries cannot show how the observed values were shaped.

The transfusion endpoint shows a related but distinct statistical issue. It is a participant-level binary outcome, not a continuous volume, and its estimate has its own scale and uncertainty. It is useful to keep the two endpoints conceptually separate rather than treating one as a direct confirmation of the other. The registry's lack of reported secondary analyses and multiplicity details further supports cautious interpretation.

Finally, the planning illustrations help distinguish a prospective design calculation from retrospective claims about power. They show how assumed effect size and a chosen power target affect planned participants per arm under stated assumptions. They do not reveal the original rationale for the trial's enrollment or turn an uncertain observed result into evidence of a definite effect. The record makes clear why effect estimates, precision, design assumptions, and reporting completeness all matter when interpreting a clinical trial.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry record leaves important design and analysis details unspecified. Eligibility criteria, recruitment setting, number of centers, randomization procedure, allocation concealment, and the roles included in masking are not reported in the registry record. These details would help readers assess how participants entered the study and how the assigned groups were protected from selection or assessment bias.

For the primary outcome, the measurement procedure and assessor are not described. The record does not say whether measurements were standardized across operations, how missing or implausible values were handled, or whether the distributions were checked. The standard deviations differ between groups, but no diagnostic information is reported. Participant-level data are not given, limiting assessment of outliers or distribution shape.

The record does not define the analysis population or provide a participant flow by outcome. Although the primary endpoint has group sizes of 42 and 46, it is not reported whether these are all randomized participants with available measurements or whether exclusions occurred. Missing-data methods, protocol deviations, crossovers, and sensitivity analyses are not reported in the registry record.

The original sample-size justification and statistical analysis plan are not reported. The record does not specify whether the primary contrast was adjusted for covariates, how multiplicity was handled, or whether prespecified subgroup or interim analyses were conducted. These features should not be inferred from the planning illustrations, which are based on the observed effect and stated planning assumptions rather than the trial's original design rationale.

The secondary transfusion outcome has no reported formal analyses. The record also does not report a clinical-importance threshold for either endpoint or a cost-efficiency result despite the study summary's stated interest in cost efficiency. Safety reporting is limited to the posted event counts and term listing; event adjudication, timing, and causal attribution are not reported. Together, these gaps constrain reproducibility and the scope of conclusions that can be drawn.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Hemostasis in Open Acetabulum and Pelvic Ring Surgery Using Tranexamic Acid — NCT02051686.
• Registry record last updated 2018-02-27; status last verified 2018-01.
• Results first posted 2018-01-30.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

22. Record Summary

NCT02051686 is a completed prospective, randomized, double-masked, parallel controlled study sponsored by University of Missouri-Columbia. It compared TXA with placebo during open acetabulum and pelvic ring surgery. The registry lists enrollment as 88; the primary outcome group sizes are 42 for TXA and 46 for placebo.

The primary endpoint was mean intra-operative blood loss on the day of surgery. The posted mean difference was 167.5 milliliters, with a confidence interval from -71.45 to 406.5 milliliters and an unadjusted p-value of 0.169. The secondary endpoint was the number requiring an allogeneic transfusion during the perioperative hospitalized period; the registry lists no reported analyses for it.

The record does not report the original sample-size justification, full statistical analysis plan, missing-data methods, or analysis populations. The posted estimates should therefore be read with their uncertainty and reporting limitations in view.