Biostatistics Introduction & Data Presentation
What is Biotatistics?
What is Statistics?
Youngstown State University
Lies and nothing but lies!?
Scientific method for understanding
and solving problem!
Measure of Central Tendency
Mean: the average value of the data.
If n observations are denoted by x1, x2, ., xn,
their (sample) mean is
Describe Distribution with Numbers
Measure of Center
Measure of Var
A Simple Example
Probability and Counting Rules
A researcher claims that 10% of a large
population have disease H.
A random sample of 100 people is taken
from this population and examined.
If 20 people in this random sample have the
Bayes Theorem & Screening Tests
If you test positive for HIV, what is
the probability that you have HIV?
If you have a positive mammogram,
what is the probability that you have
Sampling Distribution & Confidence Interval
A Normal Distribution
P(X > 225) = .382
X ~ N ( = 211, = 46)
Example: Consider the distribution of serum
cholesterol levels for 40- to 70-year-old
males living in community A has a mean of
211 mg/100 ml, and t
One-Sided Confidence Interval
Size of Interval
Two-Sided C. I.
, X + Z / 2
Z C.I.: ( X Z / 2
t C.I.: ( X t / 2
, X + t / 2
One-Sided C. I.
Examples for Inference on MultipleSamples and
1. A researcher wishes to find out whether a new diet
program can help a particular population in reducing Body
Mass Index (BMI). The BMI scores from a random sample
of subjects were record
Relative Frequency Histogram
Modeling Continuous Distribution
10 20 30 40 50 60 70 80 90 100 110
Density Function (Curve)
A smooth curve that fit