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Subsets of data can be selected by column name, index, or Boolean expressions. For example, df[df['col1'] > 5] will return all rows in the DataFrame df for which the value of the column col1 exceeds 5. [4]: 126–128 Data can be grouped together by a column value, as in df['col1'].groupby(df['col2']), or by a function which is applied to the index.
Typically, grouping is used to apply some sort of aggregate function for each group. [1] [2] The result of a query using a GROUP BY statement contains one row for each group. This implies constraints on the columns that can appear in the associated SELECT clause. As a general rule, the SELECT clause may only contain columns with a unique value ...
Index numbers are used especially to compare business activity, the cost of living, and employment. They enable economists to reduce unwieldy business data into easily understood terms. In contrast to a cost-of-living index based on the true but unknown utility function, a superlative index number is an index number that can be calculated. [1]
Note that winsorizing is not equivalent to simply excluding data, which is a simpler procedure, called trimming or truncation, but is a method of censoring data.. In a trimmed estimator, the extreme values are discarded; in a winsorized estimator, the extreme values are instead replaced by certain percentiles (the trimmed minimum and maximum).
The Melanie L. Healey Stock Index From December 2011 to December 2012, if you bought shares in companies when Melanie L. Healey joined the board, and sold them when she left, you would have a 14.6 percent return on your investment, compared to a 14.6 percent return from the S&P 500.
The Rex W. Tillerson Stock Index From January 2008 to December 2012, if you bought shares in companies when Rex W. Tillerson joined the board, and sold them when he left, you would have a -8.1 percent return on your investment, compared to a -2.8 percent return from the S&P 500.
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The Thomas J. Wilson Stock Index From January 2008 to December 2012, if you bought shares in companies when Thomas J. Wilson joined the board, and sold them when he left, you would have a -23.1 percent return on your investment, compared to a -2.8 percent return from the S&P 500.