Speaking Stata: How best to generate indicator or dummy variables

2019 ◽  
Vol 19 (1) ◽  
pp. 246-259
Author(s):  
Nicholas J. Cox ◽  
Clyde B. Schechter
Keyword(s):  
Dummy Variables ◽  
A Value ◽  
Factor Variable

Indicator or dummy variables record whether some condition is true or false in each observation by a value of 1 or 0. Values may also be missing if truth or falsity is not known, and that fact should be flagged. Such indicators may be created on the fly by using factor-variable notation. tabulate also offers one method for automating the generation of indicators. In this column, we discuss in detail how otherwise to best generate such variables directly, with comments here and there on what not to do.

scholarly journals Company mission statements and financial performance

2005 ◽  
Vol 2 (3) ◽  
pp. 28-35 ◽  
Author(s):  
Peter Atrill ◽  
Mohammed Omran ◽  
John Pointon
Keyword(s):  
Stock Returns ◽  
Service Sector ◽  
Customer Orientation ◽  
Value Relevance ◽  
Mission Statements ◽  
Return On Equity ◽  
Dummy Variables ◽  
Dummy Variable ◽  
A Value ◽  
A Company

Is there a value-relevance associated with the disclosure of a corporate mission? In this study the mission orientation of 143 UK listed companies are analysed according to their orientation towards shareholders, stakeholders, customers and markets. Performance is then analysed by means of multiple regressions, allowing for beta, gearing, size and tax, as control variables, and taking account of mission orientation by means of a dummy variable in separate regressions. As to the accounting return on equity, dummy variables were not significant in the service sector. In the non-service sector the shareholder-orientated dummy was relevant to the accounting return on equity over three years, but the overall model was not very significant. However, three-year stock returns in the service sector are strongly influenced by whether company mission is shareholder orientated or not. In the non-service sector, six-year stock returns, and also excess returns, are influenced by whether a company is stakeholder orientated or not. Mission, according to customer orientation, did not affect performance. The overall conclusion is that there may be some value-relevance attached to mission orientation, although in this sample it was invariant to customer-orientation.

scholarly journals An Econometric Model to Predict Participation in Urban and Community Forestry Programs in South Carolina, U.S.

2006 ◽  
Vol 32 (5) ◽  
pp. 229-235
Author(s):  
J. Jess Fleming ◽  
Thomas Straka ◽  
Stephen Miller
Keyword(s):  
South Carolina ◽  
Community Forestry ◽  
Econometric Model ◽  
Probability Model ◽  
Program Planning ◽  
Correct Prediction ◽  
Dummy Variables ◽  
Logit Regression ◽  
A Value ◽  
Forestry Programs

A regression-based econometric model was generated from a statewide survey of South Carolina, U.S., residents concerning participation in urban and community forestry programs. The econometric model attempts to estimate the probability of an individual’s participation. Results are intended to increase effectiveness of program planning and organization within state forestry commissions. Model 1 was created as follows: participation = F (gender, age, education, marital status, region, area raised, area reside, household, duties, and income). Because these responses represented qualitative values, a number of dummy variables (0 or 1, for example, for yes or no) were generated to more accurately reflect the values for participation and a logit model was used. Logit regression analysis produces a value between 0 and 1 that can be interpreted as a probability. Model 2, with fewer variables, was later created to reduce possible multicollinearity problems. Model 1 had a pseudo-R 2value of 0.2955 or a 29.55% probability of having a correct prediction for participation. Model 2 had a pseudo-R 2value of 0.2407. The models produced reasonable predictions of participation.

Observations of the Thermal Decomposition of Brucite

1968 ◽  
Vol 26 ◽  
pp. 446-447
Author(s):  
P. L. Burnett ◽  
W. R. Mitchell ◽  
C. L. Houck
Keyword(s):  
Thermal Decomposition ◽  
Magnesium Oxide ◽  
Basal Plane ◽  
Magnesium Ions ◽  
A Value ◽  
Reaction Proceeds

Natural Brucite (Mg(OH)2) decomposes on heating to form magnesium oxide (MgO) having its cubic ﹛110﹜ and ﹛111﹜ planes respectively parallel to the prism and basal planes of the hexagonal brucite lattice. Although the crystal-lographic relation between the parent brucite crystal and the resulting mag-nesium oxide crystallites is well known, the exact mechanism by which the reaction proceeds is still a matter of controversy. Goodman described the decomposition as an initial shrinkage in the brucite basal plane allowing magnesium ions to shift their original sites to the required magnesium oxide positions followed by a collapse of the planes along the original <0001> direction of the brucite crystal. He noted that the (110) diffraction spots of brucite immediately shifted to the positions required for the (220) reflections of magnesium oxide. Gordon observed separate diffraction spots for the (110) brucite and (220) magnesium oxide planes. The positions of the (110) and (100) brucite never changed but only diminished in intensity while the (220) planes of magnesium shifted from a value larger than the listed ASTM d spacing to the predicted value as the decomposition progressed.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

High Levels of Circulating Thrombomodulin in Human Foetuses and Children

1999 ◽  
Vol 81 (06) ◽  
pp. 906-909 ◽  
Author(s):  
Marie-Hélène Aurousseau ◽  
Danielle Gozin ◽  
Fernand Daffos ◽  
Armando D’Angelo ◽  
François Forestier ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Endothelial Cell ◽  
Protein C ◽  
Endothelial Cell Surface ◽  
A Value ◽  
Median Level ◽  
Group A ◽  
Anticoagulant Function ◽  
Cell Surface Proteoglycan ◽  
Human Foetuses

SummaryThrombomodulin (TM) is an endothelial cell surface proteoglycan with anticoagulant functions, also implicated in cell proliferation, cell-cell adhesion and differentiation. In this study we determined circulating plasma TM (pTM) levels in human foetuses at different stages of pregnancy, at birth and in childhood. TM levels increased with gestational age, the median level reaching a peak of approximately 165 ng/ml between the 23rd and 26th week, thereafter decreasing gradually, reaching a value of 108 ng/ml at birth. pTM continues to decrease progressively during childhood, reaching in the 5-15 years group a median of 56 ng/ml which approaches the adult value. The pTM peak was statistically significant and represents a specific foetal phenomenon as it was independent of the corresponding maternal values. As a whole, the pTM pattern during foetal maturation appears totally different from that of protein C, prothrombin and other coagulation activators and inhibitors and thus, TM may play in the foetus another role in addition to its well-known anticoagulant function.

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