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All animals need oxygen to metabolize nutrients to generate cellular energy. The above equation illustrates how nutrients (glucose) are converted to cellular energy in the form of adenosine triphosphate (ATP). Note carbon dioxide is produced as a by-product...

Chromosomes are molecules of DNA that provide the essential genetic code for all living organisms, and it is the code that directs the synthesis of proteins that define each organism's structure and function. Genetic factors contribute to causation of many dis...

The oldest description of cancer were written in Egypt as early as 3000 BC as part of an ancient Egyptian textbook on surgery. The word "cancer" comes from the Greek work carcinos, which means crab. Hippocrates used this term to describe the disease because t...

Atherosclerotic disease is a global health problem. Cardiovascular disease is the number 1 cause of death worldwide, claiming 12 billion lives annually in developing countries. In the US heart disease claims about 800,000 deaths per year. It is estimated 80% o...

 Questions when creating a study: Outcome of interest? Groups? Population? Type of Study? Comparative studies are intended to show differences of an outcome between two or more groups.     Cross Sectional - Collected at one point in time    Longitudi...

Probability is the study of uncertainty and randomness in the world. It measures chance. Proportion is a summary statistic. Proportion measures size (i.e. how many patients have optional blood pressure). We show the probability of Event A as P(A) The comp...

A variable is a measurement or characteristic on which individual observations are made. A random variable is a variable whose possible values are outcomes of a random phenomenon. A domain is a set of all possible values a variable can take. Discrete random v...

For any domain there are infinitely many distributions. The most common and famous distributions get a name; Binomial, Negative Binomial, Geometric, Hypergeometric, Poisson, etc. In this section we focus on Binomial and Poisson distributions. The Bernoulli Di...

A variable X follows a discrete probability distribution if the possible values of X are either: A finite set A countable infinite sequence px(xi) = P(X=xi) is called the probability mass function (PMF) px(xi)  >= 0 as it is a probability The sum of...

Social, Political and Economic There is growing recognition that there are many social determinants of health. To fully understand the impact on health we must recognize a persons character and environment. The WHO categorizes these determinates as Structura...

Since it is practically impossible to enroll the whole target population, we take a sample - a subgroup representative of the population. Since we're not examining the whole population, inferences will not be certain. Probability is the ideal tool to model and...

θ is fixed while θhat_n is a random variable which provides the single best value to estimate θ θhat is unbiased when bias = E(θhat_n) - θ = 0 θhat is consistent when θhat_n -> θ Mean squared error MSE = E(θhat_n - θ)2 = bias(θhat_n) + V(θhat_n) If bias ...

The "effect" of a particular factor on some health outcome can be described as a parameter. Statistical hypothesis testing begins with a probability model assuming there is no effect or a null hypothesis (H0) and deciding whether there is sufficient evidence t...

With categorical data, we are classifying data instead of measuring it. As a review: Notice we never use a z test, a t test is almost always more appropriate even for large samples. Likewise, for dichotomous outcomes could use a z-test but a chi-square test...

ANOVA can be used to compare the means of several populations with continuous populations simultaneously. The population variance of the dependent variable must be equal in all groups. Recall that  Which is the difference in two means over the standard err...

People are made of organs, organs are made of cells, cells are composed with genetic information. Genetics are important because we can earlier detect genetic diseases when a newborn has a genetic predisposition to disease; Ex. Cystic Fibrosis is a recessive g...

Correlation and regression attempt to describe the strength and direction of the association between two (or more) continuous variables. Pearson Correlation Recall r is an estimate of population correlation coefficient: It is always between -1 and 1. With...

Assumption in Linear Regression: Independence between observations Linearity between X and Y Homoscedasticity - the variance of Y is the same for any value of X Normally distributed Y for any fixed value of X Also, the model is also only generalizable...

One of the first known uses of regression was to study inheritance of traits from generation to generation in a study in the UK from 1893-1898. E.S. Pearson organized the collection of heights of mothers and one of their adult daughters over 18. The mother's h...

Review of Measures of Association Exposed Unexposed Disease a b m1 No Disease c d m0 n1 n0 n m1, m0, n1, and n0 are marginal totals and n is the overall total Prevalence is the proportion of sampled individuals that...