* Effect modification: effect of the main exposure on the outcome is affected by another variable. It is NOT a bias! * Case-control study: also known as retrospective study. Divided into “cases” and “controls.” If disease is rare, the odds ratio will approximate the relative risk (following subjects over time.) * Cohort study (Retrospective or prospective): divided into “exposed” and “non-exposed.” Study subjects are free of the outcome at the time the study begins. * Cross-sectional study: exposure and outcome are studied at one point in time. (Think: snapshot study) * Randomized control trial: gold standard for studying the efficacy of treatment or procedure. Subjects are randomized into experimental or control. Less bias and strong causal relationship. * Cross-over study: group of participants are randomized to one treatment for a certain period of time and the other with the alternative for that same certain period of time. Then after period ends, the groups switched treatments for the duration of the trial. * Parallel study: think “drug group vs. placebo group.” No other variables are measured

* Hazard ratio: the higher the ratio, that higher risk for hazardous events. If ratio is 1 (or value if closer to 1), then there’s little difference between the two entities * Factorial design studies: randomization of different interventions with additional study of 2 or more variables * Cluster analysis: randomization of different groups, not individuals

* Lowering the cut-off will increase its sensitivity
* Confounder: an extraneous factor which has properties linking it to the exposure and outcome of interest * Probability if test is negative, 1-negative predicative value * Observer bias: investigator’s decision is adversely affected by knowledge of exposure status. Example: It is known the ESRD is more common in black population * Respondent bias: outcome obtained by patient’s response...

...
INTRODUCTION TO NORMAL DISTRIBUTIONS
The normal distribution is the most important and most widely used distribution in statistics. It is sometimes called the "bell curve," although the tonal qualities of such a bell would be less than pleasing. It is also called the "Gaussian curve" after the mathematician Karl Friedrich Gauss. As you will see in the section on the history of the normal distribution, although Gauss played an important role in its history, Abraham de Moivre first...

...A. Genetics
Ribosomal 5S RNA can be presented as a sequence of 120 nucleotides. Each nucleotide can be represented by one of four characters: A (Adenine), G (Guanine), C (Cytosine), or U (Uracil). The characters occur with different probabilities for each person. We wish to test if a new sequence is the same as ribosomal 5S RNA. For this purpose, we replicate the new sequence 100 times and find that there are 60 A’s in the20th position. Use a 0.05 level of significance.
1. If the...

...Basic Biostatistics for Geneticists and Epidemiologists
A Practical Approach
Robert C. Elston
Department of Epidemiology and Biostatistics, Case Western Reserve University, USA.
William D. Johnson
Pennington Biomedical Research Center, Louisiana State University System, USA.
A John Wiley and Sons, Ltd, Publication
Basic Biostatistics for Geneticists and Epidemiologists
Basic Biostatistics for Geneticists and...

...I wish to apply for admission to the PhD program in Biostatistics at your esteemed university, commencing from Fall 2002 . I am currently studying in the second year of the two year Masters program in Statistics at the Indian Statistical Institute, Calcutta, known all over the world for the seminal contributions that some of its alumni have made and are continuing to make i n the field of Statistics - both theoretical and applied, after having successfully completed the three...

...Heart
1. Blockage of which of the following arteries would lead to ischemia of the apex of the heart?
a. Anterior interventricular (descending)
b. Left circumflex
c. Posterior interventricular (descending)
d. Right marginal e. Right coronary
2. If the ductus arteriosus does not spontaneously close off soon after birth (to become the ligamentum arteriosum), it may have to be surgically ligated. When clamping or ligating it, what important structure immediately behind it must be...

...MBBS & USMLE
Lead MY World has now instituted USMLE preparatory classes with MBBS degree program at the International School of Capital Medical University Beijing Peoples Republic of China. It is important to talk about what USMLE stands for, not from the standpoint of the abbreviation but the VALUE of it. It basically brings MBBS (A 6 year undergraduate clinical medicine degree of Bachelor of Medicine & Bachelor of Surgery) graduates to work in...

...Tutorial 3
Question 1
a) A company wishes to review its distribution operation and from its time sheet records it found that 144 vehicles were loaded in a 24 hour period. A frequency distribution table was prepared from the data as follows:
Time to load (minutes) Number of vehicles
40 up to 50 17
50 up to 60 61...

...Exam 1
Chapter 1
* In statistics the group we wish to study is called the population
* A sample is a subset of the population which is used to gain insight about the population. Samples are used to represent a larger group, the population.
* • Descriptive statistics – the collection, organization, analysis, and presentation of data.
* Inferential statistics – uses descriptive statistics to estimate population parameters; an educated guess about the population based on...