1. a chi-square distribution is:
a. characterized by the number of degrees of freedom
b. asymetric around 0
c. having a single peak distribution function
d. having a negative expectation

2. a fisher - snedecor distribution is:

a. characterized by the number of degrees of freedom
b. asymetric around 0
c. a particular standard normal distribution
d. having a single peak distribution function

3. a student distribution is:
a. characterized by the number of degrees of freedom
b. symmetric around the peak
c. having a single peak distribution function, more precisely above 0
d.approximately standard normal if the number of degrees of freedom is very large

the regression line:
a. is a postive number, expressing the link between an independent variable and a dependednt one
b. is a formula that always allows good predictions for the value of the dependent variable
c. is a number that is either close to 0 or to 1
d. is a formula that is always computed from data samples

the correlation coefficient between 2 random variables:
a. is a number between -1 and 1
b. is sometimes estimated by the so called Spearman coefficient
c. is estimated by the so called Pearson coefficient
d. is estimated in Excel by function CORREL

the probability of an event can be:
a. computed if we know the quota of that event
b. computed if we know the probability of the complementary event
c. estimated by a relative frequency, in case the random experiment can be repeated several times
d. subjectively estimated by a number betweeen 0 and 1

when we speak about a confidence interval:
a. it is supposed that the value of interest is inside this interval
b. the lenght of this interval is at most 1
c. we have to specify a confidence level
d. the average of sampled data has been previously computed

the X-square statistic is computed when:
a. we know the mean and the standard deviation of sampled data
b. we have at hand a set of observed data, and we expect some other data
c. we want to apply the Z tesrt of proportions
d. we have a contingencyt table

the forumla used to ocmpute the average (mean) has some properties. identify these properties:
a. most of the measured values have no influence on the result of this formula
b. the result is expressed in the same units as the measured values
c. it expresses the spread of all the measured data around thei center
d. none of the measured values is treated differently as the other

a box-and-whisker plot presents schematically some fundamental characteristics of the distribution of numeric data extracted from the individuals that are selected in the sample. identify descpritvie statistics that may be used when drawing a particular box-and-whisker plot:
a. both mean and median
b. both aplitude and asymetry
c. both variance and standard error
d. both medain and quartiles

in a contingency table, with a specific number of rows and a number of columns, each cell contains:
a. a formula used to identify the mean quality of individuals
b. a numer of individuals (possibly zero)
c. a quality that is common to all individuals belonging to the column
d. a number of positive characteristics of individuals
e. a weight attached to those individuals that fit in the respective cell

the sample mean (average) is:
a. a value that has maximum frequency mong all measured values
b. an inferential statistic, estimating our confidence is a psecific hypothesis
c. ranking all the measured data in increasinf order
d. a descriptive statistic, estimating the center of data

a percentile is:
a. a real value that expresses the lack of symmetry of the data around the center
b. a value that expresses how much the data is spread around the center
c. one of the values that divide the data series into hundred equal parts
d. another name given to any of the 2 quartiles (that differ from the median)
e. any value whose rank is larger than 100

the first quarile is:
a. the value that divides the data series into 2 equal parts
b. a statistic used to estimate the center data
c. the real value that expresses the lack of symmetry of the data series around the center
d. the value which divide the data series into 2 inequal parts, the leftmost contianing 25%

the median is:
a, a statistic used to estimate the spread of data around the center
b. always situated between the 2 genuine quartiles
c. a command used to identify how large is the computer error
d. the value that diveide the data series into 2 equal parts

the variance of dataset is:
a. the command implemented in statistical software to avoid variability of treated data.
b. a measure of the spread of data around the center
c. the value expressing the lenght of the inter-quartile interval data
d. the square of the standard deviation of the dataset