pdSize#

Purpose#

Provides size description of a panel dataset including the number of groups, number of time observations for each group.

Format#

{ num_grps, T, balanced } = pdSize(df, groupvar)#
Parameters:

  • df (Dataframe) – Contains long-form panel data with \(N_i x T_i\) rows and K columns.

  • groupvar (String) – A column vector indicating group membership for panel observations.

Returns:

  • num_grps (Scalar) – Number of groups in the panel.

  • T (Vector) – Containing number of time observations for each group.

  • balanced – Indicator if panel is balanced, report 1 for balanced data, 0 othewise.

Rtype:

Scalar

Examples#

If your group variable is the first categorical variable in your dataframe and the date variable is a GAUSS date variable and not just a numeric column, you can just pass in the panel dataframe and GAUSS will locate the group and date variables for you.

// Import data
fname = getGAUSSHome("examples/pd_ab.gdat");
pd_ab = loadd(fname);

// Take a small sample for the example
pd_smpl = pd_ab[1:4 8:11,.];

// Print our sample
print pd_smpl;

id        year        emp       wage
 1  1977-01-01     5.0410    13.1516
 1  1978-01-01     5.6000    12.3018
 1  1979-01-01     5.0150    12.8395
 1  1980-01-01     4.7150    13.8039
 2  1977-01-01    71.3190    14.7909
 2  1978-01-01    70.6430    14.1036
 2  1979-01-01    70.9180    14.9534
 2  1980-01-01    72.0310    15.4910

// Check size of panel
{ num_grps, T_2, _isbalanced } = pdSize(pd_smpl);

The above code will return:

============================================================
Group ID:              id          Balanced:             Yes
Valid cases:            8          Missings:               0
N. Groups:              2          T. Average:         4.000
============================================================
id                        T[i]     Start Date       End Date
------------------------------------------------------------

1                            4     1977-01-01     1980-01-01
2                            4     1977-01-01     1980-01-01
============================================================

Remarks#

This function takes long-form panel data. To transform wide data to long-form data see dfLonger().

This function assumes panel is sorted by group and date. Note that panel data can be sorted using pdSort().

  • If groupvar is not provided, the function defaults to the first categorical or string variable in the dataframe.

  • If datevar is not provided, the function defaults to the first date variable in the dataframe.

See also

pdsummary(), pdTimeSpans()

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