Statistical Variables

1. Statistical variables can be:

1. Discrete quantitative variables measured on a report scale
2. Continuous qualitative variables measured on a report scale
3. Quantitative variables measured on a nominal scale
4. Discrete quantitative variables measured on a nominal scale
5. Continuous qualitative variables measured on a report scale

1.  If in a series data a number of large values predominate then:

1. the distribution shows negative asymmetry
2.  the modal value is less than average
3. the tail is elongated to the left
4. the distribution has a positive asymmetry
5. the variable is binary

1. The Spearman correlation coefficient was used to study the relationship between:

1. two qualitative variables with normal distribution
2. a numerical variable and one unaccountable measured on an ordinal scale
3.  two numeric variables whose distribution form cannot be predicted
4.  two qualitative variables measured on a nominal scale
5.  two qualitative variables whose distribution form cannot be predicted

1. Chebyshev's Empirical Rule applied to a data series with a normality tendency states that:

1. about 95% of the values are in the range
2. approximately 5% of values are out of range
3.  approximately 95% of observations recorded for Z scores have values between -2 and 2
4.  approximately 68% of observations recorded for Z scores have values between -3 and 3

1. To investigate the relationship between medical expenses and family size, a social worker collects data on: family size (number of people) and the average monthly expenses incurred by them for medical purposes ($). The data recorded for 8 families are:

a) Make a graphical analysis on the existence and meaning of the link between the two variables;

 b) Measure the intensity of the relationship between variables "no. of family members" and "average monthly expenses" using the Spearman coefficient.

c) Determine the degree of heterogeneity for the associated data series of variable "no. of family members".

1. In a study on the popularity enjoyed by many local periodicals, 60 randomly selected residents of a city are asked how many publications they read on average per week, typically. Following the systematization of responses revealed that: a quarter of respondents read a single publication, 38% read two such publications, 15% read three publications, 10% read four publications, 8% read five newspapers, and the rest read six publications . Is required :

a) Build the series of absolute frequency distribution, represent it graphically and determine its asymmetry;

b) Describe the distribution of population according to the number of periodicals using central tendency indicators.

 c) Determine the degree of representativeness of the average number of publications read in a week for the entire sample.

1. For a better organization of the visiting program of a museum, the manager wants to know the visiting period, depending on the moment of the day. He registered a sample of 300 visitors for which he registered the visit length (in minutes) was split up in three groups depending on the moment of the day (between 10-14, 14-18 and 18-22). The data was processed and the following results were obtained:

How much % of the variation of visit length is due to the visiting schedule?

1. In order to analyze the evolution of the Facebook activity for one of his employers a social media manager records the number of the likes received by that Fan Page during the last 12 months.

a) Compute the index and the absolute change for the following months: 3, 6, 9, and 12.