BIOSTATISTICS

By : GENELITA S. GARCIA

Statistics is the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data.

Biostatistics is the application of statistics to a wide range of topics in biology.

Statistics

Applications of Biostatistics• Public health, including epidemiology , health services research, nutrition and environmental health• Design and analysis of clinical trials in medicine, genomics, population genetics and statistical genetics.• Ecology, ecological forecasting• Biological sequence analysis

Two Areas of StatisticsDescriptive Statistics consists of collection, organization, summarization and presentation of data

Inferential Statistics consists of generalizing from samples to populations, performing hypothesis tests, determining relationships among variables, and making predictions.

Data- are the values (measurements or observations) that the variables can assume. A collection of data values forms a data set. Each value in a data set is called datum or data value.

Variable- is a characteristic or attribute that can assume different values.

eg. Color, height, temperature, texture Population- consists of all subjects that are being

studied. sample population-part of the population or a group of

subjects selected from a population

Definition of`Terms

Nominal Scale - classifies data into mutually exclusive (nonoverlapping), exhausting categories in which no order or ranking can be imposed on the data. No ranking order can be placed on the data.

eg. Gender- male or female Religion Roman Catholic, Lutheran, Jewish or Methodist.

Ordinal Scale - classifies data into categories that can be ranked, however precise differences between the ranks do not exist.

eg. Pain level- none, mild, moderate, severe

Types of Measurement Scales:

Interval Scale- ranks data, and precise difference between units of measures do exist, however there is no meaningful zero.

eg : Temperature in °C on 4 successive days Day: A B C D Temp °C: 50 55 60 65

Ratio Scale- possesses all the characteristics of interval measurement, and there exists a true zero.

eg. Weight in pounds of 6 individuals 136, 124, 148, 118, 125, 142

Random Sampling Subjects are selected by random numbers.

Systematic Sampling Subjects are selected by using the kth number after the first subject is randomly selected from 1 through k.

Stratified Sampling Subjects are selected by dividing the population into groups ( strata) and subjects within groups are randomly selected.

Cluster Sampling Subjects are selected by using

an intact group (clusters) that is representative of the population.

Sampling Techniques

Types of Graphs HISTOGRAM

Category 1

Category 2

Category 3

Category 4

0 1 2 3 4 5 6

Series 3Series 2Series 1

BAR GRAPH

Sales

1st Qtr2nd Qtr3rd Qtr4th Qtr

Pie graph

Category 1 Category 2 Category 3 Category 40

1

2

3

4

5

6

Series 1Series 2Series 3

LINE GRAPH OR TIME SERIES GRAPH