xtsum
Summary Statistics for Panel Data

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introduction to xtsum"

introduction to xtsum"
In xtsum: Summary Statistics for Panel Data 

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

Introduction

xtsum is an R wrapper based on STATA xtsum command, it used to provide summary statistics for a panel data set. It decomposes the variable $x_{it}$ into a between $(\bar{x_i})$ and within $(x_{it} − \bar{x_i} + \bar{\bar{x}})$, the global mean x being added back in make results comparable, see [@stata].

Installation

install.packages("xtsum")

# For dev version
# install.packages("devtools")
devtools::install_github("macosso/xtsum")

Getting Started

# Load the librarry
library(xtsum)

xtsum

This function computes summary statistics for panel data, including overall statistics, between-group statistics, and within-group statistics.

Usage

xtsum(
  data,
  variables = NULL,
  id = NULL,
  t = NULL,
  na.rm = FALSE,
  return.data.frame = TRUE,
  dec = 3
)

Arguments

Example

Genral example

Based on National Longitudinal Survey of Young Women, 14-24 years old in 1968

data("nlswork", package = "sampleSelection")
xtsum(nlswork, "hours", id = "idcode", t = "year", na.rm = T, dec = 6)

The table above can be interpreted as below paraphrased from [@stata].

The overall and within are calculated over N = 28,467 person-years of data. The between is calculated over n = 4,710 persons, and the average number of years a person was observed in the hours data isT = 6.

xtsum also reports standard deviation(SD), minimums(Min), and maximums(Max).

Hours worked varied between Overal Min = 1 and Overall Max = 168. Average hours worked for each woman varied between between Min = 1 and between Max = 83.5. “Hours worked within” varied between within Min = −2.15 and within Max = 130.1, which is not to say that any woman actually worked negative hours. The within number refers to the deviation from each individual’s average, and naturally, some of those deviations must be negative. Then the negative value is not disturbing but the positive value is. Did some woman really deviate from her average by +130.1 hours? No. In our definition of within, we add back in the global average of 36.6 hours. Some woman did deviate from her average by 130.1 − 36.6 = 93.5 hours, which is still large.

The reported standard deviations tell us that the variation in hours worked last week across women is nearly equal to that observed within a woman over time. That is, if you were to draw two women randomly from our data, the difference in hours worked is expected to be nearly equal to the difference for the same woman in two randomly selected years.

More detailed interpretation can be found in handout[@stephenporter]

Using pdata.frame object

data("Gasoline", package = "plm")
Gas <- pdata.frame(Gasoline, index = c("country", "year"), drop.index = TRUE)
xtsum(Gas)

Using regular data.frame with id and t specified

data("Crime", package = "plm")
xtsum(Crime, variables = c("polpc", "avgsen", "crmrte"), id = "county", t = "year")

Specifying variables to include in the summary

xtsum(Gas, variables = c("lincomep", "lgaspcar"))

Returning a data.frame object

Returning a data.frame might be useful if one wishes to perform additional manipulation with the data or if you intend to use other rporting packages such as stargazer [@hlavac_2018_stargazer] or kabel[@zhu_2021_create].

xtsum(Gas, variables = c("lincomep", "lgaspcar"), return.data.frame = TRUE)

Other Functions

The functions below can serve as a helper when the user is not interested in a full report but rather check a specific value.

between_max

This function computes the maximum between-group in a panel data.

Usage

between_max(data, variable, id = NULL, t = NULL, na.rm = FALSE)

Arguments * data: A data.frame or pdata.frame object containing the panel data.

Example

Using pdata.frame

data("Gasoline", package = "plm")
Gas <- pdata.frame(Gasoline, index = c("country", "year"), drop.index = TRUE)
between_max(Gas, variable = "lgaspcar")

Using regular data.frame with id and t specified

data("Crime", package = "plm")
between_max(Crime, variable = "crmrte", id = "county", t = "year")

between_min

This function computes the minimum between-group of a panel data.

Usage between_min(data, variable, id = NULL, t = NULL, na.rm = FALSE)

Arguments

Value The minimum between-group effect.

Example

Using pdata.frame

data("Gasoline", package = "plm")
Gas <- pdata.frame(Gasoline, index = c("country", "year"), drop.index = TRUE)
between_min(Gas, variable = "lgaspcar")

Using regular data.frame with id and t specified

data("Crime", package = "plm")
between_min(Crime, variable = "crmrte", id = "county", t = "year")

between_sd

This function calculates the standard deviation of between-group in a panel data.

Usage

between_sd(data, variable, id = NULL, t = NULL, na.rm = FALSE)

Arguments

Value The standard deviation of between-group effects.

Examples

using pdata.frame

data("Gasoline", package = "plm")
Gas <- pdata.frame(Gasoline, index = c("country", "year"), drop.index = TRUE)
between_sd(Gas, variable = "lgaspcar")

Using regular data.frame with id and t specified

data("Crime", package = "plm")
between_sd(Crime, variable = "crmrte", id = "county", t = "year")

within_max

This function computes the maximum within-group for a panel data.

Usage

within_max(data, variable, id = NULL, t = NULL, na.rm = FALSE)

Arguments

Value The maximum within-group effect.

Example

Using pdata.frame

data("Gasoline", package = "plm")
Gas <- pdata.frame(Gasoline, index = c("country", "year"), drop.index = TRUE)
within_max(Gas, variable = "lgaspcar")

Using regular data.frame with id and t specified

data("Crime", package = "plm")
within_max(Crime, variable = "crmrte", id = "county", t = "year")

within_min

This function computes the minimum within-group for a panel data.

Usage

within_min(data, variable, id = NULL, t = NULL, na.rm = FALSE)

Arguments

Value The minimum within-group effect.

Example

Using pdata.frame

data("Gasoline", package = "plm")
Gas <- pdata.frame(Gasoline, index = c("country", "year"), drop.index = TRUE)
within_min(Gas, variable = "lgaspcar")

Using regular data.frame with id and t specified

data("Crime", package = "plm")
within_min(Crime, variable = "crmrte", id = "county", t = "year")

within_sd

This function computes the standard deviation of within-group for a panel data.

Usage

within_sd(data, variable, id = NULL, t = NULL, na.rm = FALSE)

Arguments

Value The standard deviation of within-group effects.

Example

Using pdata.frame

data("Gasoline", package = "plm")
Gas <- pdata.frame(Gasoline, index = c("country", "year"), drop.index = TRUE)
within_sd(Gas, variable = "lgaspcar")

Using regular data.frame with id and t specified

data("Crime", package = "plm")
within_sd(Crime, variable = "crmrte", id = "county", t = "year")

References



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xtsum documentation built on June 22, 2024, 7 p.m.

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