Day1 Graphics 2x2

8/10/2019 Day1 Graphics 2x2

1/10

UNIVERSITY OF COPENHAGEN

DEPARTMENT OF BIOSTATISTICS

Graphics in Stata

Klaus K. Holst

29 Sep 2014

30

40

50

60

70

80

90

1900 1920 1940 1960 1980 2000Year

Life expectancy, males

Life expectancy, females

Data 19001999

Life expectancy by gender

19001999

U.S. Life Expectancy



Graphs in stataThe main command is graph followed by the type of graph

graph twoway scatter plots, line plotsgraph matrix scatterplot matricesgraph bar bar charts

graph dot dot chartsgraph box box-and-whisker plotsgraph pie pie chartsgraph save

graph use

graph combine

plus more specialized graphs: histogram, kdensity, avplot, . . .

1 graph twoway scatter ...

2 // or

3 twoway scatter ...

4 // or

5 scatter ...



U.S. life expectancy data, 1900-1999

1 clear

2 sysuse uslifeexp

1 describe

Contains data from /Applications/Stata/ado/base/u/uslifeexp.dtaobs: 100 U.S. life expectancy, 1900-1999

vars: 10 30 Mar 2011 04:31size: 3,800 (_dta has notes)

-------------------------------------------------------------------------------storage display value

v ar ia bl e n am e t yp e f or ma t l ab el v ar ia bl e l ab el-------------------------------------------------------------------------------year int %9.0g Yearle float %9.0g life expectancyle_male float %9.0g Life expectancy, malesle_female float %9.0g Life expectancy, femalesle_w float %9.0g Life expectancy, whitesle_wmale float %9.0g Life expectancy, white malesle _w fem al e fl oa t %9. 0g Li fe e xpe ct an cy , w hi te fe ma le sle_b float %9.0g Life expectancy, blacksle_bmale float %9.0g Life expectancy, black malesle _b fem al e fl oa t %9. 0g Li fe e xpe ct an cy , b la ck fe ma le s-------------------------------------------------------------------------------Sorted by: year



Scatter plots

1 twoway scatter le year

40

50

60

70

80

lifee

xpectancy

1900 1920 1940 1960 1980 2000

Year


2/10



Scatter plots

1 twoway spike le year

40

50

60

70

80

lifee

xpectancy

1900 1920 1940 1960 1980 2000

Year



Line plots

1 twoway line le year

40

50

60

70

80

lifee

xpectancy

1900 1920 1940 1960 1980 2000

Year



Line plots

1 twoway line le year, connect(stairstep)

40

50

60

70

80

lifee

xpectancy

1900 1920 1940 1960 1980 2000

Year



SchemesA scheme specifies the overall look of the graphTo change for the session

1 set scheme s2mono

1 graph query, schemes

Available schemes are

s2color see help scheme_s2color

s 2m on o se e he lp s ch em e_ s2 mo no

s2manual see help scheme_s2manual

s2gmanual see help scheme_s2gmanual

s2gcolor see help scheme_s2gcolor

s1color see help scheme_s1color

s 1m on o se e he lp s ch em e_ s1 mo no

s1rcolor see help scheme_s1rcolor

s1manual see help scheme_s1manual

sj see help scheme_sj

economist see help scheme_economist

s2color8 see help scheme_s2color8

lean1 see help scheme_lean1

lean2 see help scheme_lean2

rbn1mono see hel scheme rbn1mono


3/10



Schemes

1 twoway line le year, scheme(s1color)

40

50

60

70

80

lifee

xpectancy

1900 1920 1940 1960 1980 2000

Year



Multiple graphs in oneOverlay multiple twoway graphs (parentheses or seperate by ||)

1 twoway (line le_male year) (line le_female year)

40

50

60

70

80

1900 1920 1940 1960 1980 2000Year

Life expectancy , males Lif e expectancy, females



Graphics options

Stata can produce nice publishable graphics results in few steps.

Axis limits chosen automatically

Legends automatically added

Axis labels automatically obtained from variable labels.

To alter we need to add options (everything after ,)General syntax of the scatter graphics command:

twoway scatter varlist[if] [in] [, options]

Options divided into subgraph (here scatter), e.g.

marker_options change look of markers (colour, size, etc.)connect_options change look of lines or connecting method

axis_choice_options associate plot with alternate axis

and options for the global graph commandtwoway_options by, name, titles, legends, axes, etc.



Graphics optionsGeneral syntax:

twoway (line ..., line_options) ///

(scatter ..., scatter_options) ///

(lfit ..., lfit_options), twoway_options

In the previous plot the y -axis label disappeared:

1 twoway (line le_male year) (line le_female year),

ytitle(Life expectancy in years)

Some twoway options:

by(varlist, ...) repeat for subgroupsnodraw suppress display of graphname(name, ...)

scheme(schemename) overall lookxtitle,ytitle Axis titles

xlabel,ylabel Axis labels positionslegend Legend options

title subtitle Graph title


4/10



Graphic optionsscattermarker options:

msymbol(symbolstylelist) shape of markermcolor(colorstylelist) colour of marker, inside and outmsize(markersizestylelist) size of markermfcolor(colorstylelist) inside or "fill" colour

mlcolor(colorstylelist) colour of outlinemlwidth(linewidthstylelist) thickness of outline

. . . , jitter options, connect options, label options, . . .

lineoptions

connect(connectstyle) how to connect pointssort[(varlist)] how to sort before connectingcmissing(y/n) missing values are ignored

lpattern(linepatternstyle) line pattern (solid, dashed, etc.)lwidth(linewidthstyle) thickness of linelcolor(colorstyle) colour of linelstyle(linestyle) overall style of line

. . .



Graphics options

1 twoway (line le_male year) (line le_female year),

ytitle(Life expectancy in years)

40

50

60

70

80

Lifee

xpectancy

iny

e

ars

1900 1920 1940 1960 1980 2000Year

Life expec tancy, males Life expectancy , females



Graphics options

If the axis label is going to be reused many times we may store it ina macro

1 local gopt ytitle(Life expectancy in years) xlabel

(1875(25)2025) title(U.S. Life Expectancy)

where we also add a little more space to the x-axis + title

1 twoway (line le_male year) (line le_female year),gopt

. . . and some different line types and colours

1 local maleline "line le_male year, color(dknavy)

lpattern(solid) connect(stairstep)"

2 local femaleline "line le_female year, color(dkorange)

lpattern(dash_dot) connect(stairstep)"

1 twoway (maleline) (femaleline), gopt



Digression: MacrosAn alias that can be dereferenced in the program everywhere(!)

1 local a 1

2 local b a b c

3 global b "Hello"

local macros lives within this scope where they were defined (i.e.the do-file or program/function).

1 di a

2 di "$b b"

1

Hello a b c

To evaluate a macro expression use =

1 local a = a+1

2 di a

2


5/10



Digression: MacrosMeta-programming with macros

1 capture drop x1 x2

2 input x1 x2

3 1 3

4 2 4

5 end

1 local idx 1 2

2 foreach i in idx {

3 list xi in 1/2

4 }

+----+| x 1 ||----|

1. | 1 |2. | 2 |

+----+

+----+| x 2 ||----|

1. | 3 |2. | 4 |

+----+



Graphics options

1 twoway (maleline) (femaleline), gopt

40

50

60

70

80

Life

expectancy

in

years

1875 1900 1925 1950 1975 2000 2025Year

L ife expec tancy, males L ife expectancy , females




Line types

1 palette linepalette

solid

dash

longdash_dot

dot

longdash

dash_dot

shortdash

shortdash_dot

blank

Line pattern palette



Symbols

1 palette symbolpalette

O Oh o oh

D Dh d dh

T Th t th

S Sh s sh

+ smplus

X x

p

Symbol palette


6/10



Colours

Customize with single-line color-colname.style (in ado-path):1

set rgb "255 100 50"



Titles, plot region

l2 l1 r1 r2

1 2 0 0 0 0 0 0 0 0 0 0 0 1 2 ringposstyle

l2title

l1title

titlesubtitle

t2title

t1title

plot region

b1title

b2title

legend

notecaption

r1title

r2title

7 title6 s ub ti tl e

2 t2

1 t1

00

000

0

0

1 b1

2 b2

3 legend

4 note5 c apt ion

where titles are located is controlled by the scheme

1 help title_options



Titles

1 #delimit ;

2 twoway (maleline) (femaleline),

3 title("U.S. Life Expectancy")

4 subtitle("1900-1999")

5 caption("Life expectancy by gender")

6 note("Data 1900-1999")7 legend(col(1) ring(0) position(11))

8 yscale(range(30 90))

9 ylabel(30(10)90)

10 name(lifeexptitles, replace);

11 #delimit cr

Position given as clock-position



Titles

30

40

50

60

70

80

90

1900 1920 1940 1960 1980 2000Year

Life expectancy, males

Life expectancy, females

Data 19001999

Life expectancy by gender

19001999



7/10



Example 2, World Life Expectancy 1998

1 sysuse lifeexp, clear

1 describe

Contains data from /Applications/Stata/ado/base/l/lifeexp.dta

obs: 68 Life expectancy, 1998

vars: 6 26 Mar 2011 09:40

size: 2,652 (_dta has notes)-------------------------------------------------------------------------------

storage display value

va ri ab le n am e ty pe fo rm at l ab el v ari ab le l ab el

-------------------------------------------------------------------------------

region byte %12.0g region Region

country str28 %28s Country

popgrowth float %9.0g * Avg. annual % growth

lexp byte %9.0g * Life expectancy at birth

gnppc float %9.0g * GNP per capita

safewater byte %9.0g *

* indicated variables have notes

-------------------------------------------------------------------------------

Sorted by:



Scatter plot matrices

1 graph matrix gnppc popgrowth lexp safewater,

2 half note("")

GNPper

capita

Avg.annual

%growth

Lifeexpectancy

at birth

safewater

0 20000 40000

0

2

4

0 2 4

50

60

70

80

50 60 70 80

0

50

100



Scatter plotsPlotting the association between GNP (on log-scale) and lifeexpectancy in North America,South America with different colours

1 twoway (scatter lexp gnppc if region==2, mcolor(

dkorange) msize(0.8)) (scatter lexp gnppc if region

==3, mcolor(dknavy) msize(0.8)),

2 xscale(log) xlabel(1000 2000 4000 8000 16000,angle

(90)) legend(order(1 "North America" 2 "South

America"))

Subsetting

Notice we have here used the if argument together with logicalexpressions to subset the scatter plots. This applies to every graphcommand!

Stratification

We can also use the by option to make different plots for differentlevels of a third variable.



Scatter plotsFrom the overlay plot using if statements:

55

60

65

70

75

80

Life

expect

ancy

atbirth

1000

2000

4000

8000

16000

GNP per capita

North America South America

DEPARTMENT OF BIOSTATISTICS DEPARTMENT OF BIOSTATISTICS


8/10



Scatter plots, by

1 twoway (scatter lexp gnppc),

2 by(region, row(1)) xsize(10)

50

60

70

80

0 10000 20000 30000 40000 0 10000 20000 30000 40000 0 10000 20000 30000 40000

Eur & C.Asia N.A. S.A.

Lifee

xpectancy

atbirth

GNP per capitaGraphs by Region



Scatter plotsLabels can be added to the graph (here we also remove the points)

1 scatter lexp gnppc if region==2,

2 mlabsize(2) mlabel(country) mlabposition(0) msymbol(i))

Canada

Dominican Republic

El Salvador

Guatemala

Haiti

Honduras

Jamaica

Mexico

Nicaragua

PanamaTrinidad and Tobago

United States

55

60

65

70

75

80

Life

expectancy

atbirth

0 10000 20000 30000 i



Scatter plots, point sizesAnd size of points depending on another variable

1 scatter lexp gnppc if region==2 [pweight=popgrowth],

msymbol(Oh)

55

60

65

70

75

80

Lifee

xpectancy

atbirth

0 10000 20000 30000



Curve fitsLinear regression (lfit, lfitci) or quadratic (qfit , qfitci)

1 twoway (lfitci lexp safewater) (scatter lexp safewater)

55

60

65

70

75

80

20 40 60 80 100safewater

95% CI Fitted values

Life expectancy at birth



9/10



Bar plots

1 graph bar (mean) lexp (p50) lexp (mean) safewater (p50)

safewater, over(region)

0

20

40

60

80


mean of lexp p 50 of lexp

mean of safewater p 50 of safewater



Box plots

Box-whisker plots

Gives a quick summary of the marginal distribution of continuousvariables. Useful for getting a quick overview of skewness, potentialoutliers etc. for many variables.

1 graph box lexp, over(region) marker(1,mlabel(country))

Box limits are the 25% and 75% quantiles and with medianmarked. as a line in the box. The whiskers shows the most extremeobservations (min/max) within 1.5IQR from the the box limits (or

else this limit).



Box plots

1 graph box lexp, over(region) marker(1,mlabel(country))

Haiti

Bolivia

55

60

65

70

75

80

Lifee

xpectancy

atbirth




Histograms, density estimation

Histograms can be generated with the syntax

1 histogram lexp, bins(#) width(#)

Selecting the width or number of bins potentially difficult, bydefault selected ad hoc from the number of observations n:

k= min{sqrt(n), 10log10(n)}

We can overlay normal approximation (option normal) ornon-parametric kernel density estimates (option kdensity), there is

also a seperate graph kdensitycommand)

1 histogram lexp, normal normopt(lpattern(dot))



10/10



Histograms

1 histogram lexp, normal normopt(lpattern(dot))

0

.02

.04

.06

.08

.1

Density

55 60 65 70 75 80Life expectancy at birth



QQ-plotsComparison with the theoretical quantiles of a normal distribution

1 qnorm lexp

50

60

70

80

Life

expectancy

atbirth

60 65 70 75 80 85

Inverse Normal



QQ-plots

1 capture drop z

2 gen z = rnormal()

3 qnorm z

Day1 Graphics 2x2

Documents

Transcript of Day1 Graphics 2x2