Univariate Descriptive Statistics Flashcards
Explain simply what is the Herfindal index composed of
The Herfindal Index is composed of the square scares of each company in a specific and defined market. For example: (2%)^2 + (89%)^2 + (13%)^2
For what is Herfindahl index used in stats?
It is defined as a common measure of market concentration
How do we calculate a concentration ratio of CR1 and what about CR3?
The concentration ratio CR1 is calculated as the share (in decimals) of the highest share holder in the market. The concentratio ratio CR3 is calculated as the sum of the shares (in decimals) of the top 3 share holders in the market. The shares are kept in decimal and they are NOT squared.
With what is the Concentration CRn calculated?
With the percentage share. Therefore, we cannot calculate with the simple profit number of relative share but exclusively with the percentage share.
While creating a Lorenz Curve, generally, on which axis do we place the population %?
Usually at the bottom, dividing according to the analysis we have to do but more generally in quintiles or in decimals.
In which case should I prefer the Normalized Gini Coefficient over the normal one?
The normalized Gini Coefficent takes into account the market size. Even if the gini coefficients are the same, only the normalized one actually reveals the market concentration weighted according to the size.
When do we use the normal average, the harmonized mean and the time series?
The harmonized mean is used for metric scales and physics values. The time series is especially used in the case of average growth rates and similars.
How do I calculate the Laspeyes Index?
I calculate the Laspeyes Index by making a division between the past quantities and prices of the product vs the past (q0) quantity*price of the same products. The Laspeyes index has the concept of having “the same basket”. Q0 means quantity at the time 0 of our observation.
What is the difference in terms of quantity between Laspeyes Index and Paasche Index?
Laspeyes makes its calculations thinking about the quantities that were used in the past and check what they would cost today. The Paasche Index calculates how much the things/quantities we eat today would cost in the past.
How do you calculate the Paasche Index?
To calculate the Paasche Index, you need to check the divisione betweent the current product costs and their CURRENT quantity vs the past product costs and STILL the CURRENT quantity. The Paasche Index is more Present oriented.
How can I know if the Moment coefficient of skweness indicates a right, simmetric, or left skew?
When the moment coefficient of Skewness if bigger than 0, it is right-skewed; if it is below 0 then it is left-skewed. If it is =0 then it is symmetric.
When I have a Platykurtic graph, what is the corresponding appearance and value of the Excess Kurtosis?
In terms of Excess Kurtosis, I will have a negative c or K. In terms of appearence this means that my peak will be lower (achatado) and my tails will be a bit fatter.
When I have a Leptokurtic graph, what is the corresponding appearance and value of the Excess Kurtosis?
In terms of Excess Kurtosis, I have a positive value. Aesthetically, I have a very high peak and thinner tails.
When I have a Mesokurtic graph, what is the corresponding appearance and value of the Excess Kurtosis?
In terms of Excess Kurtosis, we have a value equal to 0. In regards to the appearance, we are referring to a normal distribution.
How is the conversion or multiplication of factors such as Arithmetic mean possible? If I have to convert between one currency and the other, how is the mean affected?
In this case, the mean is linearly affected. That is to say, if we duplicate the value of X then automatically the mean duplicates.
Is the empirical variance affected linearly when we multiply x by 4, 5, and other numbers?
The empirical variance is not linearly affected. The empirical variance varies on the basis of the power of two. That is to say, if we have an exchange rate of 0.8 we must calculate 0.8x0.8 and then multiply this value by the empirical variance.
What are some of the characteristics of nominal variables?
- just word data like CDU
- differences between data cannot be assessed/not meaningful
- qualitative
What are some characteristics of ordinal variables?
- can be ranked and ordered
- no specific meaningful differences
What are some characteristics of ratio variables?
Ratio variables are used for metric systems and degrees.
- there is a natural zero=total absence
- diff beteeen variables are accessible and measurable
What are some characteristics of interval variables?
- diff can be assessed
- no actual zero but place holder
- negative values accessible
What is a semi continuous value?
A semi-continuous variable is a variable that is continuous over part of its range but has a significant probability mass at a single value, often zero (e.g., expenditure where many people spend $0, but others spend varying amounts).
What is a continuous variable?
A continuous variable is a quantitative variable that can take on any value within a range, including fractions and decimals (e.g., height, weight).
What is a discrete variable?
: A discrete variable is a quantitative variable that takes on countable, distinct values with no intermediate values between them (e.g., number of students in a class).
