The world’s Largest Sharp Brain Virtual Experts Marketplace Just a click Away
Levels Tought:
Elementary,Middle School,High School,College,University,PHD
| Teaching Since: | May 2017 |
| Last Sign in: | 283 Weeks Ago, 1 Day Ago |
| Questions Answered: | 27237 |
| Tutorials Posted: | 27372 |
MCS,MBA(IT), Pursuing PHD
Devry University
Sep-2004 - Aug-2010
Assistant Financial Analyst
NatSteel Holdings Pte Ltd
Aug-2007 - Jul-2017
 30. Christina conducts a study on the effects of a reading comprehension course to help first- graders who aren’t reading at their grade level. She obtains a sample of 30 children from an inner city elementary school, and 30 children from a school in the suburbs. The 30 inner-city children are the control group and don’t get the treatment, and the 30 children from the suburbs are the experimental group and get the treatment. Six months later, the children in the treatment group improved markedly in their reading, whereas the children in the control group did not. Christina’s study suffers from which threat to internal validity?
A.Instrumentation 

B.Selection 

C.Mortality 

For this assignment, I need to provide the correct answer as well as why the others are wrong. I have been unable to figure out the correct answer.
----------- Â ----------- H-----------ell-----------o S-----------ir/-----------Mad-----------am ----------- Th-----------ank----------- yo-----------u f-----------or -----------usi-----------ng -----------our----------- we-----------bsi-----------te -----------and----------- ac-----------qui-----------sit-----------ion----------- of----------- my----------- po-----------ste-----------d s-----------olu-----------tio-----------ns.----------- Pl-----------eas-----------e p-----------ing----------- me----------- on----------- ch-----------at -----------I a-----------m o-----------nli-----------ne -----------or -----------inb-----------ox -----------me -----------a m-----------ess-----------age-----------