Error message

Deprecated function: unserialize(): Passing null to parameter #1 ($data) of type string is deprecated in content_access_get_settings() (line 225 of modules\contrib\content_access\content_access.module).
content_access_get_settings('per_node', 'resource') (Line: 26)
Drupal\content_access\Access\ContentAccessNodePageAccessCheck->access(Object, Object)
call_user_func_array(Array, Array) (Line: 160)
Drupal\Core\Access\AccessManager->performCheck('access_check.content_access_node_page_access', Object) (Line: 136)
Drupal\Core\Access\AccessManager->check(Object, Object, NULL, 1) (Line: 93)
Drupal\Core\Access\AccessManager->checkNamedRoute('entity.node.content_access', Array, Object, 1) (Line: 327)
Drupal\Core\Menu\LocalTaskManager->getTasksBuild('entity.node.canonical', Object) (Line: 358)
Drupal\Core\Menu\LocalTaskManager->getLocalTasks('entity.node.canonical', 0) (Line: 95)
Drupal\Core\Menu\Plugin\Block\LocalTasksBlock->build() (Line: 171)
Drupal\block\BlockViewBuilder::preRender(Array)
call_user_func_array(Array, Array) (Line: 101)
Drupal\Core\Render\Renderer->doTrustedCallback(Array, Array, 'Render #pre_render callbacks must be methods of a class that implements \Drupal\Core\Security\TrustedCallbackInterface or be an anonymous function. The callback was %s. See https://www.drupal.org/node/2966725', 'exception', 'Drupal\Core\Render\Element\RenderCallbackInterface') (Line: 772)
Drupal\Core\Render\Renderer->doCallback('#pre_render', Array, Array) (Line: 363)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 435)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 201)
Drupal\Core\Render\Renderer->render(Array) (Line: 479)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 186)
__TwigTemplate_c5e97d19e7a31581b1264b46fb3c64f3->doDisplay(Array, Array) (Line: 405)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 378)
Twig\Template->display(Array) (Line: 390)
Twig\Template->render(Array) (Line: 55)
twig_render_template('themes/custom/agrodep/templates/layout/page.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('page', Array) (Line: 422)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 201)
Drupal\Core\Render\Renderer->render(Array) (Line: 479)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 97)
__TwigTemplate_86c443abb0414abd2cb1f01227dc5239->doDisplay(Array, Array) (Line: 405)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 378)
Twig\Template->display(Array) (Line: 390)
Twig\Template->render(Array) (Line: 55)
twig_render_template('themes/custom/agrodep/templates/layout/html.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('html', Array) (Line: 422)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 201)
Drupal\Core\Render\Renderer->render(Array) (Line: 162)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 564)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 163)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 142)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 174)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 81)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 191)
Drupal\page_cache\StackMiddleware\PageCache->fetch(Object, 1, 1) (Line: 128)
Drupal\page_cache\StackMiddleware\PageCache->lookup(Object, 1, 1) (Line: 82)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 709)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

Evaluating the Econometric Evaluations of Training Programs with Experimental Data

Authors
Robert J. LaLonde
Publisher
American Economic Association

This paper compares the effect on trainee earnings of an employment program that was run as a field experiment where participants were randomly assigned to treatment and control groups with the estimates that would have been produced by an econometrician. This comparison shows that many of the econometric procedures do not replicate the experimentally determined results, and it suggests that researchers should be aware of the potential for specification errors in other nonexperimental evaluations.

Publication date
Source / Citation
LaLonde, Robert J. "Evaluating the Econometric Evaluations of Training Programs with Experimental Data," The American Economic Review, Vol. 76, No. 4 (Sep., 1986) pp. 604-620.
Location
http://www.jstor.org/stable/1806062