Informal versus formal judgment of statistical models: The case of normality assumptions.

Researchers sometimes use informal judgment for statistical model diagnostics and assumption checking. Informal judgment might seem more desirable than formal judgment because of a paradox: Formal hypothesis tests of assumptions appear to become less useful as sample size increases. We suggest that this paradox can be resolved by evaluating both formal and informal statistical judgment via a simplified signal detection framework. In 4 studies, we used this approach to compare informal judgments of normality diagnostic graphs (histograms, Q-Q plots, and P-P plots) to the performance of several formal tests (Shapiro-Wilk test, Kolmogorov-Smirnov test, etc.). Participants judged whether or not graphs of sample data came from a normal population (Experiments 1-2) or whether or not from a population close enough to normal for a parametric test to be more powerful than a nonparametric one (Experiments 3-4). Across all experiments, participants' informal judgments showed lower discriminability than did formal hypothesis tests. This pattern occurred even after participants were given 400 training trials with feedback, a financial incentive, and ecologically valid distribution shapes. The discriminability advantage of formal normality tests led to slightly more powerful follow-up tests (parametric vs. nonparametric). Overall, the framework used here suggests that formal model diagnostics may be more desirable than informal ones.

Multicenter study to evaluate the benefits of technology-assisted workflow on i.v. room efficiency, costs, and safety.

PURPOSE: The benefits of technology-assisted workflow (TAWF) compared with manual workflow (non-TAWF) on i.v. room efficiency, costs, and safety at hospitals with more than 200 beds are evaluated. METHODS: Eight hospitals across the United States (4 with TAWF, 4 without) were evaluated, and the characteristics of medication errors and frequency of each error type were measured across the different institutions. The average turnaround time per workflow step and the cost to prepare each compounded sterile preparation (CSP) were also calculated, using descriptive statistics. RESULTS: The TAWF hospital sites detected errors at a significantly higher rate (3.13%) than the non-TAWF hospital sites (0.22%) (p < 0.05). The top error reporting category for the TAWF sites was incorrect medication (63.30%), while the top error reporting category for the non-TAWF sites was incorrect medication volume (18.34%). Use of TAWF was associated with a preparation time decrease of 2.82 min/CSP, a compounding time decrease of 2.94 min/CSP, and a decrease in overall cost to prepare of $1.60/CSP. CONCLUSION: The use of TAWF in the i.v. room was associated with the detection of 14 times more errors than the use of non-TAWF, demonstrating different frequency of error in the results. TAWF also led to a faster preparation time that had a lower cost for preparation.