Flashcards
Bioinformatik R2
Flashcards do conjunto (13)
- 1Why is probability theory important in statistics?Probability or “chance” plays an important role in Biology.
• Many biological processes are directly affected by chance:
(For example, segregation of chromosomes)
• Results of experiments can also be affected by chance (chance fluctuations in the environment)
• Probability models allow us to know how likely or unlikely the result of an
experiment is.
(When we collect data we
don’t collect data from an
entire population. Instead we
only take a sample from a
population.) - 2What is the propability (E) of an event?the proportion of times it is expected to happen if
repeated over and over again under the same conditions.
Pr(E) = # ways to get outcome E
Total number of outcomes - 3Addition ruleTwo events where one OR the other happens can be added.
When rolling a die what is the probability of getting 1 or 2 or 3 or 4 or
5? - 4What are joint or disjoint events?disjoint= without intersection
PR(E1)+PR(E2) (black hair or red hair)
joint= with overlapping (What is the probability of a man having
blue eyes given that he has black hair?)
PR(E1)+PR(E2)- PR(E1 togehter with E2) - 5What is a conditional probability ?propabilty of one event happening, giving that another happened.
What is the probabilty of the man having blue eyes given that he has black hair
PR(E1|E2)= PR (E1 together with E2) / PR (E1) - 6What are complement in probabiltyThe complement of an event E consists of all the outcomes that aren’t E.
• This is calculated as: Pr(Complement of E) = 1 - Pr(E) - 7What is the Multiplication rule?The chance of two events both happen is the chance of
the first multiplied by the chance of the second, given
that the first event happens.
(Wahrscheinlichkeits-Baum) - 8How would you calculate the probabilty of not rolling a sixPr{E} = 1 − (5/
6) × (5/
6) = (11/
36) - 9What are some probability distributions?1. Normal Distribution
2. Binominal distribution
3. Poisson Distribution - 10What can one say about histogramms?discriptive statistic
• Along the x axis we have ALL possible outcomes, and on the y axis we have
bars that represent the probability of each outcome.
The total area under a probability distribution is 1 or 100%. - 11with which parameters are normal distributions described?the mean (denoted by μ) and the
variance (denoted by σ2)
X ~ N(μ,σ2) - 12What is a binominal distribution?A variable is binomially distributed when it only has two possible outcomes.
For example:
• Yes (1) or No (0), - 13What are the parameters of the binominal distribution?number of trials n, and the
probability of success for each trial p.
X ~ B(n,p)
n =number of trials
k = number of successes
p= the probability of
success of each trial.
Pr(X = k) = (n über
k) p^k(1 − p)^(n−k)
Informações
- Descrição
- probabilities
- Criado por
- Usuário eliminado · set 2024
- Atualizado
- 14 set 2024
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- Criado por Alicia L · 14 set 2024
- Copiado por Alicia L · 14 set 2024
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