Two-level factorial experiments

Smucker, Byran J.; Krzywinski, Martin; Altman, Naomi

doi:10.1038/s41592-019-0335-9

Cited by 11 publications

(20 citation statements)

References 4 publications

(6 reference statements)

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“…2). Non-numeric characteristics were dummy binary coded as "0" for the reference and "1" for the other levels; regression measures the change in the response when the characteristic changes by one level [48]. The post-dosimetry values of the penalty scores were also assessed as additional predictors of the prone penalty score reduction.…”

Section: Methodsmentioning

confidence: 99%

Is prone free breathing better than supine deep inspiration breath-hold for left whole-breast radiotherapy? A dosimetric analysis

et al. 2021

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Purpose The advantage of prone setup compared with supine for left-breast radiotherapy is controversial. We evaluate the dosimetric gain of prone setup and aim to identify predictors of the gain. Methods Left-sided breast cancer patients who had dual computed tomography (CT) planning in prone free breathing (FB) and supine deep inspiration breath-hold (DiBH) were retrospectively identified. Radiation doses to heart, lungs, breasts, and tumor bed were evaluated using the recently developed mean absolute dose deviation (MADD). MADD measures how widely the dose delivered to a structure deviates from a reference dose specified for the structure. A penalty score was computed for every treatment plan as a weighted sum of the MADDs normalized to the breast prescribed dose. Changes in penalty scores when switching from supine to prone were assessed by paired t-tests and by the number of patients with a reduction of the penalty score (i.e., gain). Robust linear regression and fractional polynomials were used to correlate patients’ characteristics and their respective penalty scores. Results Among 116 patients identified with dual CT planning, the prone setup, compared with supine, was associated with a dosimetric gain in 72 (62.1%, 95% CI: 52.6–70.9%). The most significant predictors of a gain with the prone setup were the breast depth prone/supine ratio (>1.6), breast depth difference (>31 mm), prone breast depth (>77 mm), and breast volume (>282 mL). Conclusion Prone compared with supine DiBH was associated with a dosimetric gain in 62.1% of our left-sided breast cancer patients. High pendulousness and moderately large breast predicted for the gain.

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Section: Methodsmentioning

confidence: 99%

Is prone free breathing better than supine deep inspiration breath-hold for left whole-breast radiotherapy? A dosimetric analysis

et al. 2021

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“…The scheduled experiment (3 2 factorial design) was aimed at obtaining stable dispersions of lipid nanoparticles suitable for the incorporation of the iridoid glycosides under study (aucubin and catalpol). Statistical analysis conducted using the 3 2 factorial design [ 22 , 23 ] involved evaluating the impact of certain independent variables (solid lipid and nonionic surfactant content) on the dependent variables representing the basic physicochemical parameters of lipid nanoparticles (Z-ave: mean particle size, PDI: polydispersity index, ZP: zeta potential). The measured data obtained by determining the values of the dependent variables for all prepared samples of the lipid nanoparticle dispersions are listed in Table 1 and then analyzed statistically with the help of Statistica 10.0 software.…”

Section: Resultsmentioning

confidence: 99%

Lipid Nanoparticles Loaded with Iridoid Glycosides: Development and Optimization Using Experimental Factorial Design

2021

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Lipid nanoparticles based on multiple emulsion (W/O/W) systems are suitable for incorporating hydrophilic active substances, including iridoid glycosides. This study involved optimization of composition of lipid nanoparticles, incorporation of active compounds (aucubin and catalpol), evaluation of stability of the resulting nanocarriers, and characterization of their lipid matrix. Based on 32 factorial design, an optimized dispersion of lipid nanoparticles (solid lipid:surfactant—4.5:1.0 wt.%) was developed, predisposed for the incorporation of iridoid glycosides by emulsification-sonication method. The encapsulation efficiency of the active substances was determined at nearly 90% (aucubin) and 77% (catalpol). Regarding the stability study, room temperature was found to be the most suitable for maintaining the expected physicochemical parameter values (particle size < 100 nm; polydispersity index < 0.3; zeta potential > |± 30 mV|). Characterization of the lipid matrix confirmed the nanometer size range of the resulting carriers (below 100 nm), as well as the presence of the lipid in the stable β’ form.

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“…Factorisation experiments are used in many disciplines, with early applications being in agricultural field experiments (Fisher, 1926), and widespread application in industrial and engineering design (Box et al, 2005) and other fields such as medicine (e.g. Smucker et al, 2019). The experiments that underpin such analysis are called "factorial experiments".…”

mentioning

confidence: 99%

“…In this paper, we focus on factorisation of numerical model simulations of the climate system; in this case, the factorisation typically consists of attributing a fundamental property of the climate system to multiple internal model parameters and/or boundary conditions. In common with previously proposed factorisation methods in this field (Stein and Alpert, 1993;Lunt et al, 2012), we limit our analysis to the case where there are two possible values for each variable, and where all combinations of all variables have been simulated; such an experimental design is called a 2 k (or two-level) full factorial experiment (Montgomery, 2013). Also in common with these studies, we assume that there is zero (or negligible) uncertainty in each simulation, which is consistent with the deterministic nature of most climate models.…”

mentioning

confidence: 99%

“…Also in common with these studies, we assume that there is zero (or negligible) uncertainty in each simulation, which is consistent with the deterministic nature of most climate models. Factorisation has been applied extensively in the climate literature; some examples include Claussen et al (2001), Hogrefe et al (2004), van den Heever et al (2006), and Schmidt et al (2010); see also the collected studies in Alpert and Sholokhman (2011). The factorisation method proposed by Stein and Alpert (1993) has currently been cited more than 280 times according to Web of Science.…”

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confidence: 99%

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Multi-variate factorisation of numerical simulations

et al. 2021

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Abstract. Factorisation (also known as “factor separation”) is widely used in the analysis of numerical simulations. It allows changes in properties of a system to be attributed to changes in multiple variables associated with that system. There are many possible factorisation methods; here we discuss three previously proposed factorisations that have been applied in the field of climate modelling: the linear factorisation, the Stein and Alpert (1993) factorisation, and the Lunt et al. (2012) factorisation. We show that, when more than two variables are being considered, none of these three methods possess all four properties of “uniqueness”, “symmetry”, “completeness”, and “purity”. Here, we extend each of these factorisations so that they do possess these properties for any number of variables, resulting in three factorisations – the “linear-sum” factorisation, the “shared-interaction” factorisation, and the “scaled-residual” factorisation. We show that the linear-sum factorisation and the shared-interaction factorisation reduce to be identical in the case of four or fewer variables, and we conjecture that this holds for any number of variables. We present the results of the factorisations in the context of three past studies that used the previously proposed factorisations.

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Two-level factorial experiments

Cited by 11 publications

References 4 publications

Is prone free breathing better than supine deep inspiration breath-hold for left whole-breast radiotherapy? A dosimetric analysis

Is prone free breathing better than supine deep inspiration breath-hold for left whole-breast radiotherapy? A dosimetric analysis

Lipid Nanoparticles Loaded with Iridoid Glycosides: Development and Optimization Using Experimental Factorial Design

Multi-variate factorisation of numerical simulations

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