Christensen KB, Makransky G, Horton M Critical Values for Yen's Q3: Identification of Local Dependence in the Rasch Model Using Residual Correlations. Appl Psychol Meas. 2017 May;41(3):178-194. doi: 10.1177/0146621616677520. Epub 2016 Nov 16.
Feng X, Luo S, Li J, Yue D, Xi J, Zhu W, Gao X, Guan X, Lu J, Liang Z, Zhao C Fatty infiltration evaluation and selective pattern characterization of lower limbs in limb-girdle muscular dystrophy type 2A by muscle magnetic resonance imaging. Muscle Nerve. 2018 Oct;58(4):536-541. doi: 10.1002/mus.26169. Epub 2018 Sep 3.
Hung M, Clegg DO, Greene T, Saltzman CL Evaluation of the PROMIS physical function item bank in orthopaedic patients. J Orthop Res. 2011 Jun;29(6):947-53. doi: 10.1002/jor.21308. Epub 2011 Mar 15.
Hung M, Voss MW, Bounsanga J, Gu Y, Granger EK, Tashjian RZ Psychometrics of the Patient-Reported Outcomes Measurement Information System Physical Function instrument administered by computerized adaptive testing and the Disabilities of Arm, Shoulder and Hand in the orthopedic elbow patient population. J Shoulder Elbow Surg. 2018 Mar;27(3):515-522. doi: 10.1016/j.jse.2017.10.015. Epub 2018 Jan 9.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.