a cura della classe IE scientifico a.s. 2011-12 con la guida della prof.ssa M. Montanarelli

2. Statistics is the study of the collection,
organization, analysis and interpretation of
data. It deals all aspects of this, including the
planning of data collection in terms of the
design of surveys and experiments.

3. Descriptive statistics summarize the population data by describing
what was observed in the sample numerically or graphically.
Numerical descriptors include mean and standard deviation for
continuos data types (like heights or weights), while frequency and
percentage are more useful in terms of describing categorial data
(like race).

4. In statistics, mean
has two related
meanings:
 the arithmetic mean
(and is distinguished
from the geometric
mean or harmonic
mean).
 the expected value
of a random variable ,
which is also called
the population mean.

5. There are other statistical measures that should not be confused
with averages – including ‘median’ and ‘mode’. Other simple
statistical analyses use measures of spread, such as range,
interquartile range, or standard deviation. For a real-valued random
variable X, the mean is the expectation of X. Note that not every
probability distribution has a defined mean (or variance).

6. Standard deviation is a widely used measure of
variability or diversity used in statistics and probability
theory. It shows how much variation or “dispersion”
exists from the average (mean, or expected value). A
low standard deviation indicates that the data points
tend to be very close to the mean, whereas high
standard deviation indicates that the data points are
spread out over a large range of values.

7. ESEGUITO DA
MANUEL DE CHIARA
VALERIE DE CHIARA
FRANCESCO FORTUNATO
ANTONIO VERNI