Biostatistics

Code:

CN11002

Acronym:

BIOEST

Keywords
Classification	Keyword
OFICIAL	Physical Sciences

Instance: 2017/2018 - 1S

Active?	Yes
Course/CS Responsible:	Nutrition Sciences

Cycles of Study/Courses

Acronym	No. of Students	Study Plan	Curricular Years	Credits UCN	Credits ECTS	Contact hours	Total Time
CNUP	108	Plano oficial	1	-	3	42	81

Teaching language

Portuguese

Objectives

In the end of the semester, the students should be aware of the importance of the statistics in the scientific investigation. This chair has the objective of motivating the students to make an analysis of the statistical aspects of the studies they find or make.
To achieve that objective, the students should have a notion of what is population and sample and be able to distinguish different types of random variables.
In the analysis of data, the students should be able to compute the mean, median, mode, percentile, quartile, variance, standard deviation, skewness and kurtosis, both when the data is a statistical series or grouped in classes. The students should be able to present and understand data in tables and in graphs.
The students should be able to evaluate the relationship between pairs of variables, in particular, they should be able to interpret Pearson and Spearman correlation coefficients, the values of Cohen's k and odds ratio. They should be able to understand the concept of hypothesis testing and to interpret some common tests.
The students will need to make simple computations on probability, to distinguish independent events from exclusive events and to understand the definition of conditional probability. It will be important to know the difference between probability and odds. The students should also be able to interpret some probability functions, probability density functions and cumulative probability functions and they should be able to compute the expected value and the variance.

Learning outcomes and competences

Awareness of the importance of the statistics in the scientific investigation.

Ability to make an analysis of the statistical aspects of studies.

Aquisition of the notion of what is population and sample.

Ability to distinguish different types of random variables.

Computation of means, medians, modes, percentiles, quartiles, variances, standard deviations, skewness and kurtosis.

Presentation and understanding of data in tables and in graphs.

Ability to evaluate the relationship between pairs of variables (interpretation of odds ratio, Cohen's k, Pearson and Spearman correlation coefficients and understanding the concept of hypothesis testing).

Making simple computations on probability, distinguishing independent events from exclusive events, understanding the definition of conditional probability, and knowing the difference between probability and odds.

Interpretation of some probability functions, probability density functions and cumulative probability functions.

Computing the expected values and variances.

Working method

Presencial

Pre-requirements (prior knowledge) and co-requirements (common knowledge)

It is expected that the students have the following previous knowledge:
- Computation of descriptive statistic measures (namely frequencies, mean, median, mode and standard deviation).
- Classical definition of probability and combinatorics (combinations and partial permutatios with and without repetition).

Program

1 Random variable:
a) Notions of random variable, population and sample;
b) Simple random sampling;
c) Scales of measurement of random variables: nominal, ordinal, interval, ratio, discrete and continuous.
2 Descriptive statistics:
a) Statistical series and grouped data;
b) Conversion of statistical series in grouped data – Sturges' formula;
c) Tables of frequency, relative frequency, cumulative frequency, cumulative relative frequency, density and relative density;
d) Graphical representation of data: Stem and Leaf diagram, box and whiskers diagram, bar chart, histogram, frequency polygons and density polygons;
e) Localization parameters: Mean, Median, Mode, Quartile and Percentile;
f) Dispersion and shape parameters: variance (with Sheppard's correction), standard deviation, dispersion coefficient, skewness and kurtosis.
3 Relation between pairs of variables:
a) Scatter plots, Pearson and Spearman correlation coefficients;
b) Crosstabs, agreement and Cohen's k and odds ratio;
c) Hypothesis testing - introduction;
d) Application examples of t-Student's test and of qui-square test for the independence.
4 Probability theory:
a) Axiomatic definition of probability;
b) Independent, complementary, exclusive and mutually exclusive events;
c) Conditional probability;
d) Total Probability Theorem and Bayes' Theorem.
e) Notion of probability function, probability density function and cumulative distribution function;
f) Expected value and variance of a random variable.

Mandatory literature

Daniel Wayne W.; Biostatistics. ISBN: 0-471-16386-4
Guimarães Rui Campos; Estatística. ISBN: 972-8298-45-5

Complementary Bibliography

Clegg Frances; Estatística para todos. ISBN: 972-662-411-8

Teaching methods and learning activities

Theoretic classes (1h00/week): expository and interrogative method.
Theoretical-practice classes (1h00/week): interrogative and demonstrative method, with the resolution of exercises.
Laboratory classes (1h00/week): interrogative and demonstrative method, with the resolution of exercises in a computer.

Software

SPSS
Excel
R

keywords

Physical sciences > Mathematics > Statistics > Medical statistics
Physical sciences > Mathematics > Statistics

Evaluation Type

Distributed evaluation with final exam

Assessment Components

Designation	Weight (%)
Exame	80,00
Participação presencial	20,00
Total:	100,00

Amount of time allocated to each course unit

Designation	Time (hours)
Estudo autónomo	42,00
Frequência das aulas	39,00
Total:	81,00

Eligibility for exams

For a student (in the ordinary regimen) to be eligible for exam at Bioestatistics, he/she must not have more than the legal limit of missed classes (without proper justification) nor he/she may have a practical classes grade below 9.5 points (out of 20). To pass at this chair, he/she must obtain at least 8.0 points (out of 20) in the written exam and a final grade of at least 9.5 points (out of 20).
Each student will have a practical classes grade according to his/her participation on classes and his/her assiduity to the classes.

Students eligible for the Biostatistics exams in one of the two previous academic years can be dispensed from classes. Their final grade will be computed having in consideration their best practical classes grade in this academic year and the two previous ones.

Calculation formula of final grade

The evaluation of the classes in which the student was present A, between 0 and 20, is computed in the following way:

A = 10 + na/Na + (nap + 2 * soma(ai) / am) * 4 / Na , where na is the number of classes in which the student was present, Na is the number of classes in the semester, nap is the number of classes with positive participation, ai is the evaluation of the participation in each class, and am is the maximum grade of the class evaluation.

The presential evaluation AP, between 0 and 20, results from the application of the penalty due to each unjustifyed missed classes, being computed from the expression:

AP = 0.5 * (2 - pf - pf^2) * A , where  pf is the proportion, between 0 and 1, of unjustified missed classes in the semester.


Students are required to do a group work, jointly with Methodologies for Food Consumption Assessment, to be evaluated from an oral presentation. The classifications T, betwen 0 and 20, have in consideration the following items:
- Dificulty of the statistical techniques (25%);
- Scientific correction (25%);
- Deepness and critical analysis in the Nutrition Sciences (25%);
- Presentation quality (25%).


The practical classes grade P, between 0 and 20, is computed in the following way:

P = 0.5 * AP + 0.5 * T.


The final grade F, between 0 and 20, is computed in the following way:

F = 0.8 * E + 0.2 * max(P, E), where E represents the written exam grade.


In the written exam, the answers must be written in blue or black ink in the given sheets. It will not be allowed the use of corrective (white) ink. Scientific calculators will be allowed, provided they have not the ability of plotting graphs and are not programmable. Furthermore, it will not be allowed the use of equipment with the ability of remote communication.

Special assessment (TE, DA, ...)

Students may request, until the end of October, excuse fromattending the classes (TP and PL). For the students that were excused, the final grade will only be the written exam grade.
Students that are not enrolled in Methodologies for Food Consumption Assessment will have access to a database in order to do their practical assessment.

Observations

The support schedule will be the following:
- Monday, from 18h00 to 18h45, Rui Poínhos, room B340;
- Tuesday, from 13h30 to 15h00, Bruno Oliveira, room B339;
- Wednesday, from 18h00 to 19h30, Bruno Oliveira, room B339.
To avoid periods of large affluence of students, we ask to schedule personally or by email up to the beginning of the afternoon of the previous weekday.

The support schedule during the examination period will be 5h before the exam of the Normal period and 5h before the exam of the Recouse period. The support schedule will be arranged after the publication of the exam calendar and will be available inside the Documents of Biostatistics.