Understanding Disease Frequency: Incidence, Prevalence, and Public Health Measures
Definition of Proportion
- A measure that states a count relative to the size of the group.
- A ratio in which the numerator is part of the denominator.
- May be expressed as a percentage.
Definition of Rate
- A ratio that consists of a numerator and a denominator and in which time forms part of the denominator.
- Contains the following elements:
- Disease frequency
- Unit size of population
- Time period during which an event occurs
Example of Rate Calculation
Definition of Prevalence
The number of existing cases of a disease
Read MoreCore Statistical Concepts and Applications
Linear Regression: Test Scores vs. Hours Studied
Consider the following linear regression equation: Test Scores = 45 + 5(Hours Studied)
- The Test Scores variable is the outcome variable. It is what the model is trying to predict.
- Hours Studied is the explanatory variable. It is used to explain or predict changes in the test scores.
- The slope coefficient associated with Hours Studied is 5. This indicates that for every additional hour spent studying, the model predicts an increase of 5 points in the test
Statistics Concepts: Observational Studies, Bias, and Inference
Statistics Concepts and Definitions
Ex. 1:
Observational study: No cause-effect; just associations. Five Number Summary = Min, Q1, Median, Q3, Max
Factors: Explanatory variable (x). Covariance: + or – relation but not strength
Block design: Individuals sharing the same characteristic are pooled.
SRS (Simple Random Sample); Stratified: Sample distinct groups separately then combine them. Sample survey: Cross-sectional; collect data of a population at one point in time.
Multistage: Using SRS within SRSs.
Read MoreProbability Rules and Statistical Estimation Methods
Probability Theory Fundamentals
Probability Definition
Probability measures the likelihood that an event will occur.
- The probability of an event A is often denoted as P(A). It can be calculated as: P(A) = m / n
- m = number of favorable outcomes for event A
- n = total number of possible outcomes
- P(A) represents the theoretical probability of event A.
Probability is a basic tool in the study and application of statistical methods. Medicine, for instance, often involves probabilistic reasoning.
Properties of
Read MoreKey Concepts in Statistics: Data Analysis and Probability
Key Concepts in Statistics
Data and Variables
Statistics: A branch of science that deals with collecting, organizing, analyzing, interpreting, summarizing, and presenting data.
Unit/Individual: An object on which we take a measurement or observation (e.g., people, places, things).
Population: The collection of all individuals or units under consideration.
Sample: A subset of the population from which we obtain data.
Variable: Any characteristic or property of an individual.
- Quantitative Data: Numerical
Understanding Key Statistical Concepts and Theorems
Law of Large Numbers
If you take samples of larger and larger size from any population, then the mean (x̄) of the sample tends to get closer and closer to μ (the population mean).
Sampling Distribution
The sampling distribution of the mean approaches a normal distribution as n (the sample size) increases.
Central Limit Theorem
The larger the sample size, the more normal the distribution will be.
Standard Error
The standard error is the standard deviation of the distribution of the sample means. T-distributions