Internal Validity

2017 ◽  
Author(s):  
Richard McCleary ◽  
David McDowall ◽  
Bradley J. Bartos
Keyword(s):  
Time Series ◽  
Internal Validity ◽  
Control Group ◽  
Synthetic Control ◽  
Donor Pool ◽  
Control Time ◽  
Data Control ◽  
Rubin's Causal Model ◽  
Definition Of ◽  
And Control

Chapter 7 begins with an outline and description of five threats to internal validity common to time series designs: history, maturation, instrumentation, regression, and selection. Given the fundamental role of prediction in the modern scientific method, scientific hypotheses are necessarily causal. After an outline of the evolving definition of “causality” in the social sciences, contemporary Rubin causality or counterfactual causality is introduced. Under the assumption that subjects were randomly assigned to the treatment and control groups, Rubin’s causal model allows one to estimate the unobserved causal parameter from observed data. Control time series are chosen so as to render plausible threats to internal validity implausible. An appropriate control time series may not exist, however, an ideal time series may be possible to construct. Synthetic control group models construct a control time series that optimally recreates the treated unit’s preintervention trend using a combination of untreated donor pool units.

scholarly journals KADAR KALSIUM GIGI YANG TERLARUT PADA PERENDAMAN MINUMAN ISOTONIK

e-GIGI ◽  
2015 ◽  
Vol 3 (2) ◽  
Author(s):  
Syahril Panigoro ◽  
Damajanty H. C. Pangemanan ◽  
Juliatri .
Keyword(s):  
Time Series ◽  
Enamel Surface ◽  
Tooth Surface ◽  
Control Group ◽  
Acid Attack ◽  
Series Design ◽  
Time Series Design ◽  
Control Time ◽  
And Control ◽  
Very High

Abstract: Dental enamelis a tissuethat experience a very high and susceptibleprocess ofmineralizationto acid attack. The composition ofdrinksthat contain lots ofacidwillaccelerate the damageto the tooth surface. Isotonic drink is one of several carbonated or noncarbonated products to improve fitness, which contains sugar, citric acid, and minerals. Isotonicdrinkshavea low pH that cancausedemineralization ofthe enamel surface and continuous demineralizationwill formporosity on the enamel surface and it can cause thedissolution ofmineralcalcium. This study aims to determine the solubility of calcium in teeth soaking in the isotonic drinks. This research was a laboratory experiment with control time series design. The samples used in this study were four post extraction permanent premolar teeth which are divided into treatment group and control group. Based on this study it can be concluded that the level of the teeth calcium dissolved in the immersion of isotonic drink is 0.005 ppm.Keywords: isotonic drinks, teeth calcium dissolutionAbstrak:Email gigi merupakan suatu jaringan yang mengalami proses mineralisasi yang sangat tinggi dan rentan terhadap serangan asam. Komposisi minuman yang banyak mengandung asam akan mempercepat kerusakan pada permukaan gigi. Minuman isotonik merupakan salah satu dari beberapa produk minuman ringan karbonasi atau nonkarbonasi untuk meningkatkan kebugaran, yang mengandung gula, asam sitrat, dan mineral. Minuman isotonik mempunyai pH rendah yang dapat menyebabkan demineralisasi permukaan email gigi dan demineralisasi yang terus menerus akan membentuk porositas pada permukaan email gigi sehingga dapat menyebabkan larutnya mineral kalsium. Tujuan penelitian ini untuk mengetahui besar kelarutan kalsium pada perendaman gigi dalam minuman isotonik. Penelitian ini merupakan penelitian eksperimen laboratoriumdengan desain penelitian control time series design. Jumlah sampel yang digunakan dalam penelitian ini sebanyak empat buah gigi premolar permanen post ekstraksi yang dibagi menjadi dua kelompok perlakuan dan kontrol. Berdasarkan penelitian yang dilakukan dapat disimpulkan bahwa kadar kalsium gigi yang terlarut pada perendaman minuman isotonik adalah sebesar 0,005 ppm.Kata kunci: minuman isotonik, kelarutan kalsium gigi

scholarly journals When is a Match Sufficient? A Score-based Balance Metric for the Synthetic Control Method

2020 ◽  
Vol 8 (1) ◽  
pp. 209-228
Author(s):  
Layla Parast ◽  
Priscillia Hunt ◽  
Beth Ann Griffin ◽  
David Powell
Keyword(s):  
Los Angeles ◽  
Control Method ◽  
Control Unit ◽  
Treated Group ◽  
Control Group ◽  
Synthetic Control ◽  
Donor Pool ◽  
Synthetic Control Method ◽  
The Mean ◽  
The Impact

AbstractIn some applications, researchers using the synthetic control method (SCM) to evaluate the effect of a policy may struggle to determine whether they have identified a “good match” between the control group and treated group. In this paper, we demonstrate the utility of the mean and maximum Absolute Standardized Mean Difference (ASMD) as a test of balance between a synthetic control unit and treated unit, and provide guidance on what constitutes a poor fit when using a synthetic control. We explore and compare other potential metrics using a simulation study. We provide an application of our proposed balance metric to the 2013 Los Angeles (LA) Firearm Study [9]. Using Uniform Crime Report data, we apply the SCM to obtain a counterfactual for the LA firearm-related crime rate based on a weighted combination of control units in a donor pool of cities. We use this counterfactual to estimate the effect of the LA Firearm Study intervention and explore the impact of changing the donor pool and pre-intervention duration period on resulting matches and estimated effects. We demonstrate how decision-making about the quality of a synthetic control can be improved by using ASMD. The mean and max ASMD clearly differentiate between poor matches and good matches. Researchers need better guidance on what is a meaningful imbalance between synthetic control and treated groups. In addition to the use of gap plots, the proposed balance metric can provide an objective way of determining fit.

scholarly journals Assessment of the impact of the employment roadmap on the unemployment rate of the Republic of Kazakhstan: synthetic control method

2021 ◽  
pp. 121-130
Author(s):  
T. S. Sokira ◽  
Z. T. Myshbayeva
Keyword(s):  
Unemployment Rate ◽  
Control Method ◽  
Action Plan ◽  
Control Group ◽  
Synthetic Control ◽  
Donor Pool ◽  
Synthetic Control Method ◽  
The Republic ◽  
The Impact ◽  
Weighted Combination

The purpose of the research is to assess the impact of the action plan of the Employment Roadmap on the unemployment rate in Kazakhstan.Methodology. Synthetic Control Method was used in this paper. The method, which compares one or more units exposed to the event and determines what would have happened if the unit had not been treated. In other words, this method creates a weighted combination of control states to create a single «synthetic» control group, in order to approach the counterfactual unit in Kazakhstan in the absence of a plan or Roadmap.The originality / value of the research based on the analysis, panel data from Kazakhstan and 13 donor pool countries for the period 2000-2019 were taken for modeling.Findings: As a result of the study, it was revealed that the unemployment rate would have been 2% higher in 2019 if Kazakhstan had not adopted an action plan in the form of an Employment Roadmap in 2009.

scholarly journals Using an Experience of the European Union to Form Future Preschool Teachers’ Ecological Competence

2021 ◽  
Vol 13 (1) ◽  
pp. 262-280
Author(s):  
Liudmyla Zahorodnia ◽  
Iryna Danylchenko ◽  
Tetiana Marieieva
Keyword(s):  
Environmental Safety ◽  
Control Group ◽  
The European Union ◽  
Literary Sources ◽  
The Future ◽  
Preschool Educators ◽  
Definition Of ◽  
Methodological Aspects ◽  
And Control ◽  
Experimental Group

The article is dedicated to the theoretical and methodological aspects of the future preschool educators’ ecological competence formation with using the European Union’s experience in environmental safety and education. The aim of the study is to verify the effectiveness of the implementing the European Union’s experience in the process of the future preschool educators’ ecological competence forming. The authors analyzed domestic and foreign researches on the problem of teacher’s ecological competence. Based on the analysis of literary sources and own experience of teaching activity in the institution of higher education authors gave the definition of the concept "future preschool teacher’s ecological competence", identified and characterized its structural components. A complex of theoretical (analysis, synthesis, comparison, modelling, systematization, generalization) and empirical (testing, observation, pedagogical experiment; methods of mathematical statistics) methods was used to achieve the aim of the research. 92 students (experimental group (n = 45) and control group (n = 47)) of Oleksandr Dovzhenko Hlukhiv National Pedagogical University participated in the study. It has been determined that the teaching the course "Implementing the Strategy of Environmental Security: Integration of European Experience" to the students of the experimental group had a positive effect on the levels of their ecological competence formation.

scholarly journals Impact of Vitamin C and Thiamine Administration on Delirium-Free Days in Patients with Septic Shock

2020 ◽  
Vol 9 (1) ◽  
pp. 193 ◽  
Author(s):  
Jong Eun Park ◽  
Tae Gun Shin ◽  
Ik Joon Jo ◽  
Kyeongman Jeon ◽  
Gee Young Suh ◽  
...  
Keyword(s):  
Septic Shock ◽  
Propensity Score ◽  
Vitamin C ◽  
Control Group ◽  
Matched Pairs ◽  
Control Groups ◽  
Icu Delirium ◽  
Definition Of ◽  
And Control ◽  
The Impact

Sepsis is a common cause of delirium in the intensive care unit (ICU). Recently, vitamin C and thiamine administration has been gaining interest as a potential adjunct therapy for sepsis. We investigated the impact of early vitamin C and thiamine administration on ICU delirium-free days among critically ill patients in septic shock. We performed a single-center, retrospective study of patients who visited the emergency department (ED) from January 2017 to July 2018. We categorized patients into a treatment (received vitamin C and thiamine) and control group. We compared delirium-free days within 14 days after ICU admission using propensity score matching. Of 435 patients with septic shock, we assigned 89 propensity score-matched pairs to the treatment and control groups. The median delirium-free days did not differ between treatment (11, interquartile range [IQR] 5–14 days) and control (12, IQR 6–14 days) groups (p = 0.894). Secondary outcomes were not different between the two groups, including delirium incidence and 28-day mortality. These findings were consistent after subgroup analysis for patients who met the sepsis-3 definition of septic shock. Vitamin C and thiamine administration showed no association with ICU delirium-free days among patients in septic shock.

Efficacy of Imagery and Meditation Techniques in Treating Psoriasis

1989 ◽  
Vol 8 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Louise Gaston ◽  
Jean-Charles Crombez ◽  
Jacques Joly ◽  
Sheilagh Hodgins ◽  
Marc Dumont
Keyword(s):  
Time Series ◽  
Multivariate Regression ◽  
Multivariate Regression Analysis ◽  
Control Group ◽  
Control Groups ◽  
Treatment Groups ◽  
Series Design ◽  
Significant Difference ◽  
The Mean ◽  
And Control

Using a dismantled time-series design, eighteen subjects were randomly assigned to three groups: meditation ( N = 5); meditation and imagery ( N = 4); waiting list ( N = 5). Treatment lasted twelve weeks, while pre- and post-baseline periods were of four weeks. An assessment control group control was also used during baseline periods ( N = 4). The severity of psoriasis symptoms was reliably rated by dermatologists. While controlling for extraneous factors influencing psoriasis symptoms, a time-series multivariate regression analysis revealed a significant difference between the mean psoriasis ratings of treatment and control groups after treatment (partial r = .30, p < .01). No additional impact was associated with the use of the imagery technique (partial r = − .06, p > .05). Four subjects in the treatment groups, two in each condition, succeeded in clinically improving their psoriasis symptoms, and none deteriorated. The practice of mediation may be clinically effective for some patients in reducing their psoriasis symptoms.

scholarly journals The effect of reduced unemployment duration on the unemployment rate: a Synthetic Control Approach

2020 ◽  
Vol 9 (1) ◽  
pp. 46-73
Author(s):  
Luzius Stricker ◽  
Moreno Baruffini
Keyword(s):  
Unemployment Rate ◽  
Control Method ◽  
Weighted Average ◽  
Control Unit ◽  
Unemployment Duration ◽  
Control Group ◽  
Synthetic Control ◽  
Donor Pool ◽  
Control Approach ◽  
The Impact

This paper examines the impact of the fourth partial revision of the law of unemployment insurance (AVIG) on unemployment dynamics in Switzerland at a cantonal level. The authors apply the Synthetic Control Method (SCM), a matching method for comparative case studies. A counterfactual analysis of the cases studied is performed by combining a control group of several untreated units, which provides a better comparison to the treatment group than a single unit. The control unit is designed as a weighted average of the available cantons in the donor pool, taking into account the similarities between the chosen controls and the treated unit. Once policy changes are controlled, the results suggest a significant effect on the unemployment rate at a cantonal level: the reform had a discernible impact on lowering the unemployment rate in the Italian- and French-speaking cantons in Switzerland.

Interrupted Time Series Analysis

2019 ◽  
Author(s):  
David McDowall ◽  
Richard McCleary ◽  
Bradley J. Bartos
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Model Building ◽  
Interrupted Time Series ◽  
Control Group ◽  
General Strategy ◽  
Synthetic Control ◽  
Interrupted Time Series Analysis ◽  
Formal Proofs ◽  
Series Analysis

Interrupted Time Series Analysis develops a comprehensive set of models and methods for drawing causal inferences from time series. Example analyses of social, behavioural, and biomedical time series illustrate a general strategy for building AutoRegressive Integrated Moving Average (ARIMA) impact models. The classic Box-Jenkins-Tiao model-building strategy is supplemented with recent auxiliary tests for transformation, differencing and model selection. New developments, including Bayesian hypothesis testing and synthetic control group designs are described and their prospects for widespread adoption are discussed. Example analyses make optimal use of graphical illustrations. Mathematical methods used in the example analyses are explicated assuming only exposure to an introductory statistics course. Design and Analysis of Time Series Experiments (DATSE) and other appropriate authorities are cited for formal proofs. Forty completed example analyses are used to demonstrate the implications of model properties. The example analyses are suitable for use as problem sets for classrooms, workshops, and short-courses.

scholarly journals Impact of Harvest Time and Pruning Technique on Total CBD Concentration and Yield of Medicinal Cannabis

Plants ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 140
Author(s):  
Danilo Crispim Massuela ◽  
Jens Hartung ◽  
Sebastian Munz ◽  
Federico Erpenbach ◽  
Simone Graeff-Hönninger
Keyword(s):  
Plant Biomass ◽  
Biomass Accumulation ◽  
Dry Weight ◽  
Control Group ◽  
Harvest Time ◽  
Medical Cannabis ◽  
Medicinal Cannabis ◽  
Definition Of ◽  
And Control ◽  
The Impact

The definition of optimum harvest and pruning interventions are important factors varying inflorescence yield and cannabinoid composition. This study investigated the impact of (i) harvest time (HT) and (ii) pruning techniques (PT) on plant biomass accumulation, CBD and CBDA-concentrations and total CBD yield of a chemotype III medical cannabis genotype under indoor cultivation. The experiment consisted of four HTs between 5 and 11 weeks of flowering and three PTs-apical cut (T); removal of side shoots (L) and control (C), not pruned plants. Results showed that inflorescence dry weight increased continuously, while the total CBD concentration did not differ significantly over time. For the studied genotype, optimum harvest time defined by highest total CBD yield was found at 9 weeks of flowering. Total CBD-concentration of inflorescences in different fractions of the plant’s height was significantly higher in the top (9.9%) in comparison with mid (8.2%) and low (7.7%) fractions. The T plants produced significantly higher dry weight of inflorescences and leaves than L and C. Total CBD yield of inflorescences for PTs were significantly different among pruned groups, but do not differ from the control group. However, a trend for higher yields was observed (T > C > L).

scholarly journals Case study in training of diagnostics of mechanisms of psychological defense in a conflict situation

2019 ◽  
Vol 66 ◽  
pp. 01002
Author(s):  
Nadezhda Sivrikova ◽  
Tatyana Ptashko ◽  
Elena Chernikova ◽  
Artem Perebeynos ◽  
Svetlana Roslyacova ◽  
...  
Keyword(s):  
Defense Mechanisms ◽  
Conflict Situation ◽  
Control Group ◽  
Effective Technique ◽  
Group 13 ◽  
Psychological Defense ◽  
Study Results ◽  
Definition Of ◽  
And Control

The relevance of a research is dictated by need of training of specialists in the field of management of the conflicts. Researchers recognize need of development of skills of overcoming barriers of effective resolution of conflicts. Defense mechanisms are such barriers. Creation a case study of training of definition of defense mechanisms in a conflict became a research objective. First, cases of video were created. Secondly, the scheme of the analysis of manifestations of mechanisms of protection in the conflict was created. The created cases were used for training of future specialists in management of the conflicts (23 people). The experimental plan with pre-post-testing and control group (13 people) was used for approbation of the created case study. Results of approbation a case study showed that it is an effective technique of formation of skills of definition of defense mechanisms in a conflict situation.

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