Transcript Example

‘If your experiment
needs statistics, you
should have done a
better experiment.’
Ernest Rutherford
‘There are
three types of
lies: lies, damn
lies, and
statistics!’
Benjamin
Disraeli
‘In God we trust. All others must bring data.’
SOFIA UNIVERSITY ‘ST. KLIMENT OHRIDSKI’
FACULTY OF BIOLOGY
BIOSTATISTICS
Approaches to teaching and future
perspectives of e-learning
Dr. Elena Tasheva-Terzieva
BIOSTATISTICS

Information about the course



Laboratory tutorials







Structure
Good practices – applets, calculators, icons, various
examples, detailed instructions, programming
Monitoring and discussions
Assessment


Syllabus
Resources
Assessment system
Current assessment and Grading
Analysis of the results
Future perspectives
Question time
Information about
the course
Course title: Biostatistics
Level of course:
Specialization:
Bachelor Level
Biology, Ecology
Number of ECTS
credits allocated:
5
number of hours:
30 hours lectures and
30 hours lab tutorials
Year of study:
3-rd Year
Assessment methods:
Written Examination
Semester:
6-th Semester
Language of instruction:
The course is in Bulgarian
language
Information about
the course
Syllabus
Syllabus
1.
2.
Introduction to biostatistics
•
•
•
•
Scope, goals and objectives
Applications of biostatistics
History of biostatistics
Computer programs for computation and graphs
Major terms
•
•
•
•
•
Populations
Samples – requirements and characteristics
Methods of sampling
Variables, types of variables
Data presentation
Syllabus
3.
Frequency distribution
•
•
•
4.
data arrangement
- why the data have to be arranged?
- statistical arrays
Types of frequency tables
Presenting data
Descriptive statistics
•
•
•
•
Sample statistics
Means (arithmetic, geometric, harmonic, root mean
square, median, mode)
Measures of variability (range, variance, STD, CV)
Graphic presentation
Syllabus
5.
6.
Introduction to Probability theory
•
•
•
•
•
Major terms
Probability - definition
Probability of compound events
Conditional probability
Applications in biology
Probability distribution
•
•
•
•
•
Introduction
Binomial distribution
Poisson distribution
Negative binomial distribution
Applications
Syllabus
7.
8.
Normal probability distribution
•
•
•
•
Properties of normal distribution
Normal distribution functions
Skewness and Kurtosis
Applications
Estimation of population parameters
•
•
•
Sample statistics v. population parameters
standard errors
confidence limits
Syllabus
9.
Tests for difference
•
Hypotesis testing, null and alternative
hypotheses
• significance level, p-value, types of error, power
of test
• Parametric and non-parametric statistics
Student t-test, paired t-test, Fisher F-test, MannWhitney U-test, Wilkoxon’s test for matched
pairs
10.
Analysis of Frequencies
•
•
Kolmogorov-Smirnov test
X2-test
Syllabus
11.
12.
Introduction to analysis of variance
•
•
•
Basic terms, applications
One-way and two-way ANOVA
Nonparametric Kruskal-Wallis test
Correlation
•
•
•
Purpose of correlation analysis
Coefficients of correlation
correlation and causal relationships
Syllabus
13.
Regression analysis
•
•
•
•
•
Regression and correlation
Linear Regression
Coefficients of regression , regression
equation and regression lines
Method of least squares
Non-linear Regression
Graphic presentation
Syllabus
14.
Planning of experiments
•
•
•
•
•
Formulation of biological problem
Choice of suitable biostatistical method
Determination of sample size
Interpretation of results
Graphic presentation
Information about
the course
Resources
Resources
 Textbooks
 On-line
e-books
 Presentations
of the lectures
Textbooks





Sokal, R. & James Rohlf. 1997. Biometry. W.H.Freeman & Co., New York.,887.
Zar, Jerrold H. 1997. Biostatistical analysis. –
Prentice-Hall, Inc., 663.
Lakin, G.F. 1990. Biometry. - М.: Vissh. Shk.,
352. [in Russian]
Fowler, Jim. 1997. Practical statistics for field
biology. – John Wiley & Sons Ltd., 223.
Pentecost, Allan. 1999. Analysing
enviromental data. – Longman, 214.
On-line e-books
http://davidmlane.com/hyperstat/index.html
Presentations of the lectures
 All
slides, used in the lectures are
available on the internet
•
•
synopsis
current information
Laboratory tutorials
Laboratory tutorials
Structure
Structure of
exercises
Good practices
 Applets
and calculators
 Icons
 Various
examples
 Detailed instructions
 Programming
Laboratory tutorials
Applets
Applets
http://www.statisticalengineering.com/histogram.htm
Calculators
http://davidmlane.com/hyperstat/z_table.html
Laboratory tutorials
Icons
Icons
Remind
Examine
Check
Icons
calculate
draw a graph
make a decision
save the results
Laboratory tutorials
Examples
Introduction to a problem
The effective population size is the size of an
ideal population, one that meets all the HardyWeinberg assumptions. In case of populations,
which size fluctuates in time, the effective
population size is calculated as a harmonic
mean.
Examine the graph for fluctuation in the size
of a population of Troglodytes troglodytes
in the UK.
Harmonic mean
Example:
Calculate the effective size of a
population given the following sizes
for four different periods of time:
200, 150, 50 и 300.
Introduction to a problem
Phenilketonuria is an autosomal recessive disease.
The locus lies on chromosome 12.
phenylalanine hydroxylase
Such individuals are unable to synthesize an enzyme,
named phenylalanine hydroxylase (PAH) which
catalyses catabolism of phenylalanine.
Bayes’ theorem
Example:
An individual is known to have parents which are both
heterozygous for allels at a locus which causes
Phenylketonuria. This individual has a normal phenotype.
What is the chance that she is the carrier for the disease?
Remember Bayes’ formula
Calculate the conditional probability:
P (carrier I normal phenotype)
Introduction to a problem
Dermatoglyphics is the scientific study of fingerprints. There are three major groups of dermal ridge
patterns: arches, loops, and whorls. The ridge count
is obtained by joining the points from the center of
the pattern to the triradius and counting the ridges
crossed
line. дъга
Total ridge
count (TRC)
is the
проста
дъга by this
t-образна
примка
симетрична
sum of ridge counts on all fingers of both hands.спирала
завита
спирала
simple arch
whorl - spiral
T arch
сложна
спирала
loop
whorl - symmetrical
whorl – double loop
Wilkoxon paired-sample test
Example:
In order to examine the inheritance of
dermatoglyphic characters, TRC of mothers and
their daughters were counted.
Which test for differences would you use
and why?
Calculate test statistics!
Introduction to a problem
Almost all species of ground beetles
(fam. Carabidae) are beneficial predators
in agroecosystems. However there are
some mixophagous species such as
Pseudoophonus griseus. Seeds are only
a part of the adult beetles diet but in
some cases they are reported as
polyphagous agricultural pests.
The feeding preferences of
the adult individuals to
different types of cultivated
and wild plant seeds could be
established experimentally.
Kruskall-Wallis test
Example:
Test design: Beetles were kept for 48 h without feeding.
Preferences for seven types of seeds were then tested
(choice test): alfalfa, pea, winter wheat rye-grass, common
bent grass, cock’s foot and timothy-grass. The average
number of attacked seeds per day was counted.
Analyze the obtained data by
nonparametric test Kruskall-Wallis!
Draw a graph to illustrate the test!
What is your conclusion about beetles
preferences to the different seed types?
Laboratory tutorials
Lab instructions
Lab instructions

Detailed lab instructions for work with
computer programs
They are available on the internet and can be
read in advance to optimize class work.
Lab instructions
Laboratory tutorials
Programming
Computer programs
Software for data analysis
Software for creation of graphs
User-defined data transforms
Programs for optimization set up of frequency
tables and calculation of class intervals, class
limits, marks and frequencies.
User-defined data transforms
Program for calculation of mean, p, q,
Binomial coefficients, probabilities and
theoretical frequencies
Laboratory tutorials
Monitoring &
discussions
Assessment
Assessment
 Assessment
system
 Grading
 Current
assessment - tests
 Analysis of the results
Assessment system
in Bulgaria
Grading
II part
III part
25%
25%
25%
25%
I part
Tests
Multiple-choice questions
When the class interval increases:
А.
B.
C.
D.
The number of classes increase
The number of classes decrease
The class marks change
The cumulative frequency of last class
decreases
The concentration of red cells in the blood of
lizards (Sceloporis occidentalis), infected by
Plasmodium and of non-infected ones was
measured. One might expect that malaria would
reduce the red cell count.
Which parametric test can be used to compare the
two samples?
What is the null hypothesis?
What is the alternative hypothesis?
Define the terms: population, degree of
freedom, significance level.
Points (MCQ)  N(right answers) - N(wrong answers)
Points (other qn' s)   coeff. i  N(right answers) i
Total points  Points (MCQ)  Points (other qn' s)
Final points % 
Total points
Best results
 100
Assessment
Analysis of the
results
Ðåçóëòàòè îTest
ò ²âèresults
òåñò ï î çî î ëî ãèÿ
60
50
40
òî ÷êè
30
20
10
0
-10
-20
-30
âåðí
î òãî âî ðè
right èanswers
ãðåø
í èanswers
î òãî âî ðè
wrong
N right answers
N wrong answers
Points
x
max
min
35.7
9.1
26.6
49
22
45
23
1
13
Áðî é òîof
÷êè
ï î ñï åöèàëí
î ñòè
Number
points
by majors
50
40
30
20
10
0
BC
ÁÕ
GB
ÃÁ
Number of points by groups
Ãåî ãðàô èÿ &
è áèî
ëî ãèÿ
Geography
Biology
Áèî ëî ãèÿ
è õèì èÿ
Biology
& Chemistry
40
50
35
40
30
25
30
20
20
15
10
10
5
0
0
1
2
3
áðî
é òî ÷êè
points
rightè
âåðí
wrong
ãðåø
íè
1
2
3
points
áðî
é òî ÷êè
right è
âåðí
ãðåø
wrongí è
Future perspectives in
e-learning
Biostatistics
attendance
part
summary
lectures
laboratory
tutorials
extramural
part
web-based
learning system
assessment
web-base
learning system
theory
support
system
exercises
communication
system
examples
information
forum
instructions
internet
resources
FAQ
dictionary
e-mail
tests
Different specializations
BSc
MSc
PhD
Database
Medicine
Biology
Agronomy
Advantages
 Elaboration
of unique teaching
materials
 Non-linear structure
 Fast remote access to information
 Independency from time and place of
classes and their duration
 Individual training
Requirements
 Initial
budget to procure necessary
equipment and software
 Qualification of lecturers/tutors
 Adaptation of studying material
 Appropriate design
 Easy navigation
Question time