 # Summary The analysis of biological data

ISBN-10 0981519407 ISBN-13 9780981519401
220 Flashcards & Notes
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Remember faster, study better. Scientifically proven. • ## 1.3 Types of data and variables

• If we want to assess how high blood pressure leads to  strokes, what is the explanatory variable? Why?
High blood pressure is the explanatory variable, since it predicts the risk of getting a stroke (response variable)
• What is the difference between nominal categorical data and ordinal categorical data?
Nominal categorical data means the categories have no inherent order. (names)
Ordinal categorical data can be ordered, despite of lack magnitude on the ordinal scale. (stage, score, size class etc.)
• ## 1.4 Frequency distributions and probability distributions

• What does the frequency distribution describe about the variable of a sample?
The frequency distribution describes how many times each value of a variable occurs in a sample
• What is the difference and the relation between a probability distribution and a normal distribution?
A probability distribution describes the whole population.
A
normal distribution is a theoretical probablity distribution of a continuous variable.
• Which type of treatment assignment is classified as an observational study?
When nature assigns treatment groups of values of an explanatory variable to the individuals.

• ## 2.2 Quantiles of a frequency distribution

• What does a quantile of an observation describe?
The value below which the quantile of observation lies. F.e. A quantile of 0.10, means that 10% of the observations lie below the observation.
• What does a percentile of an observation desribe?
The percentage of observations that lie below the observation.
• ## 3 Describing data

• What do descriptice statistics do?
They are quantities that capture important features of frequency distributions.
• ## 3.1 Arithmetic mean and standard deviation

• What is the most common metric to describe a frequency distribution?
The (arithmetric) mean
• What is the relationship between the variance and the standard deviation?
The sd is calculated form the variance, as the square root of the variance.