Instrumental variable methods Sample Clauses

Instrumental variable methods. When examining post randomisation variables, such as dose, confounding may occur even in the randomised clinical trial scenario. The instrumental variable design offers, under certain assumptions, the opportunity to tame confounding bias, without directly observing all confounders. The instrumental variable approach is well developed in the context of linear regression (Xxxxxxxxxx 2010) and generalised linear models (Xxxxxxxxxxxx and Goetghebeur 2003). Tchetgen Tchetgen (Tchetgen Xxxxxxxx, Xxxxxx et al. 2015) develop the instrumental variable approach in a survival context. He describes two strategies utilising Aalen’s additive hazard model (Aalen 1989). The first approach is analogous to that commonly used for estimation in linear models; the two stage least squares approach. Here, the fitted value from the first stage regression of exposure on the instrumental variable is entered in place of the exposure in the second stage hazard model to give an estimate of causal effect. The second approach is the two stage residual inclusion (TSRI); here the residual from the first stage regression of the exposure on the instrumental variable is added as a confounding control covariate to the additive hazards regression model for the exposure effect. This work utilises the second approach. A correct instrumental variable analysis rests on three fundamental assumptions (Xxxxxxx and Savitz 1997, Greenland 2000, Xxxxxxx, Xxxxxxx et al. 2006)
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  • Construction Methods No four course of brick-work, with three joints, shall exceed in height, when built, one inch more than the same bricks piles upon one another without mortar. The bricks are to be well soaked in water before use on works, in proper through so as to be thoroughly wet when layed. The Cessation of the bubbles through the water is an irldication of saturation being complete. For ensuring thorough soaking of the bricks every one or two bricklayers or more as necessary, shall be provided with tubs for use The wall of structures shall be carried up regularly in all cases 1` when the nature of the work will admit of it not leaving any part 915mm (3 feet) lower than another. Horizontal courses shalI be straight, level and even and faces of walls smooth and plumb. A straight edge and a plumb- xxx shall be used for constant checking during progress of the work. No brick-bats shall be permitted to be used except when necessary for obtaining the dimension of the different course or for obtaining the specified bond. All unfinished work must be raked back in course unless otherwise directed arid when new work is to be jointed to it the surface of unfinished work must be cleaned and wetted. The bricks shall be laid by placing sufficient mortar on the wall and forcing every brick into it in such a manner as to completely fill every joint with moratar whether at the bottom, side or end of the brick. The mortar to be used shall be that specified for the relevant schedule items and shall comply with the specification for the mortar specified. The bound used shall be English and shall be carried throughout the work. At all angles forming the junction of any two walls, the bricks shall, at each alternate course be carried into each of the respective walls, so as to thoroughly unite the work. V'Jhen the faces are to be plastered, the joints shall be well raked out before any plaster is laid on should the plaster from want of proper joint ranking detach and 7 fall off from the brick work, the contractor shall strip off the plaster bodily to the extent ordered by Superintending Engineer and shall re-do the work properly at his own expense. All requisite scaffolding shall be provided at the contractor's expense and shall be double i.e., must it have two sets of upright supports Care must be taken to ensure the safety of the work people and the contractor must comply with such instructions as the Superintending Engineer may issue to ensure such safety. The contractor will be entirely responsible for any damage or injuries to person or property resulting from ill-erected scaffolding, defective ladders, or otherwise arising out of his default in this respect. The brick work for the retaining wall shall proceed side by side with the depositing and compacting of earth between the retaining walls. At no time shall the brick-work be constructed more than 405mm (1'-4") above Y the compacted earth. In the retaining wall weep-holes shall be provided at suitable intervals as instructed during execution, with the inner surface of the weep-holed plastered 20mm (3/4") thick in cement mortar 1:4 crouched rock of grades in different layer shall be provided at the inner end of the weep-holes to prevent the choking of the weep-holes to have full drainage. No extra payment will be made for this and no deductions will be made for this in the brick-work.

  • DATA FOR CALCULATIONS The initial calculations for any payments owing under this Agreement shall be based upon the valuations placed upon the Qualified Property by the Appraisal District in its annual certified appraisal roll submitted to the District pursuant to § 26.01 of the TEXAS TAX CODE in or about July of each year of this Agreement. The certified appraisal roll data shall form the basis from which any and all amounts due under this Agreement are calculated, and the data utilized by the Consultant will be adjusted as necessary to reflect any subsequent adjustments by the Appraisal District to the District’s appraisal roll. Any estimates used by the Consultant to make calculations as required by this Agreement shall be based on the best and most current information available. The Consultant shall from time to time adjust the data utilized to reflect actual amounts, subsequent adjustments by the Appraisal District to the District’s certified appraisal roll, or any other relevant changes to material items such as student counts or tax collections.

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  • Particular Methods of Procurement of Goods Works and Services (other than Consultants’ Services)

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