Task 2: The characteristic score. Flashcards
Statistic is
the science of learning from data.
Data can be
Numerical and qualitative
Cases are
the objects described by a set of data.
A label is a
special variable used in some data sets to distinguish the different cases.
A variable is
the characteristic of a case.
Variables can be
Categorical (places the case into a group)
Quantitative (takes numerical values for which arithmetic operations make sense).
Distribution of a variable tells us
what values it takes and how often it takes these values.
Explanatory data analysis
Statistical tools and ideas that help us examine data to describe their main features.
Categorial representations of a set of variables are
Bar graphs (more flexible) and pie charts (include all categories that make up a whole).
Quantitative representations are made with the help of..
Stemplots (work better for small numbers that are greater than 0);
and
Histograms (columns don’t have spaces between them).
Tails of the distribution contain..
the extreme values.
The two principles of data examination:
1- plot your data
2- look for an overall pattern and any striking deviations.
When examining a distribution, take the further three steps:
1- Overall patterns + striking deviations
2- Look at the shape (does it have modes = major peaks)
3- Is it symmetric? (mirror image)
4- Is it skewed? (skewed to the right if the right tail is longer)
5. Outliers.
An outliers is
an individual value that falls outside the overall pattern.
We can measure the centre with the help of:
The mean x(bar) and the median M.