Course on BiostatisticsPart 1

What is statistics?

Dr. Nicolas Padilla Raygoza

Department of Nursing and Obstetrics

Division of Health Sciences and Engineering

Campus Celaya Salvatierra

University of Guanajuato, Mexico

Biosketch

Medical Doctor by University Autonomous of Guadalajara. Pediatrician by the Mexican Council of Certification on

Pediatrics. Postgraduate Diploma on Epidemiology, London School of

Hygiene and Tropical Medicine, University of London. Master Sciences with aim in Epidemiology, Atlantic

International University. Doctorate Sciences with aim in Epidemiology, Atlantic

International University. Professor Titular A, Full Time, University of Guanajuato. padillawarm@gmail.com raygosan@ugto.mx

Competencies

The reader will describe what is statistics. He (She) will describe what is descriptive and

inferential statistics. He (She) will know what are the applications

of statistics.

Introduction

Statistics The number that we obtain by count o

measure things. Procedures to analyze the data.

Descriptive statistics It is the methods to describe an data set. We use it to organize, to summary and to

present the values of data.

Introduction

Statistics Last, “the science and art of collecting,

summarizing, and analyzing data that are subject to random variation”.

It is classified into: Descriptive Inferential

Descriptive statistics - Examples

In a cohort study on risk factors to coronary heart disease, it was measure the levels of cholesterol in blood; we can show the mean and standard deviation.

Level cholesterol in blood X = 268 S ± 49

Descriptive statistics-Examples

In a cross-sectional study in a group of

children, it was determine the gender of the

subjects and it was determine

frequency and percentage of

males and females; it can be shown in graphical

form.

Variable n %

Sex

Male

Female

64

36

64

36

Total 100 100

Inferential statistics

It use the probability theory to obtain conclusions of a population, from data obtained in a sample.

It is very hard to study all population, because of this, we study samples.

Methods for estimations and hypothesis tests are important to obtain inferences.

Inferential statistics - Examples

In a National survey on the danger of smoking, we cannot interview all population, only we can interview a sample of it.

To measure prevalence of amebiasis in a population, we study a random sample. With the prevalence of the sample, we can obtain the estimate of prevalence of amebiasis in the population.

Applications of statistics

To obtain a sample. To summary data. Make inferences of a population, based in the

result of the sample. To obtain a simple model for a data set.

Bibliografia

1.- Last JM. A dictionary of epidemiology. New York, 4 ed. Oxford University Press, 2001:173.

2.- Kirkwood BR. Essentials of medical ststistics. Oxford, Blackwell Science, 1988: 1-4.

3.- Altman DG. Practical statistics for medical research. Boca Ratón, Chapman & Hall/ CRC; 1991: 1-9.

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