# 2.3 Sample selectivity bias  (Page 4/6)

 Page 4 / 6

We are interested in only a subset of these data. Table 2 reports the definitions of variables that are relevant for our analysis. We can get further insight into the data set using the summarize command. Table 3 reports the summary statistics for the data set.

 Variable name Definition country County of residence (categorical variable equal to 0, 1, ..., 9) age Age of the woman education Number of years of education of the woman married Dummy variable equal to 1 if the woman is married and 0 otherwise children Number of children that the woman has in their household wage Hourly wage rate of the woman lw Natural logarithm of hourly wage rate work Dummy variable equal to 1 if the individual is in the workforce and 0 otherwise
 Variable Obs Mean Std. Dev Min Max Age 2000 36.208 8.28656 20 59 education 2000 13.084 3.045912 10 20 married 2000 .6705 .4701492 0 1 children 2000 1.6445 1.398963 0 5 wage 1343 23.69217 6.305374 5.88497 45.80979 lw 1343 3.126703 .2865111 1.772402 3.824498 work 2000 .6715 .4697852 0 1

We are interested in modeling two things: (1) the decision of the woman to enter the labor force and (2) determinants of the female wage rate. It might be reasonable to assume that the decision to enter the labor force by a woman is a function of age, marital status, the number of children, and her level of education. Also, the wage rate a woman earns should be a function of her age and education.

## The decision to enter the labor force

We can use a probit regression to model the decision of a woman to enter the labor force. The results of this estimation are reported in Table 4. However, we can use the predict command to produce some results that we can use to be sure that we understand what the regression results mean. In particular, type in the following two commands:

.predict zbhat, xb

.predict phat, p

These two commands will predict (1) the linear prediction (zbhat) and (2) the predicted probability that the woman will be in the workforce (phat). Table 5 reports the values of these two variables for observations 1 through 10.

 . probit work age education married children Iteration 0: log likelihood = -1266.2225 Iteration 4: log likelihood = -1027.0616 Probit estimates Number of obs = 2000 LR chi2(4) = 478.32 Prob>chi2 = 0.0000 Log likelihood = -1027.0616 Pseudo R2 = 0.1889 work Coef. Std. Err. z P>z [95% Conf. Interval] age .0347211 .0042293 8.21 0.000 .0264318 .0430105 education .0583645 .0109742 5.32 0.000 .0368555 .0798735 married .4308575 .074208 5.81 0.000 .2854125 .5763025 children .4473249 .0287417 15.56 0.000 .3909922 .5036576 _cons -2.467365 .1925635 -12.81 0.000 -2.844782 -2.089948
 Observation zbhat phat 1 -0.68900 0.24541 2 -0.20290 0.41961 3 -0.48067 0.31538 4 -0.16818 0.43322 5 0.34859 0.63630 6 0.58758 0.72159 7 0.97357 0.83486 8 0.45978 0.67716 9 0.01799 0.50718 10 0.32628 0.62790

#### Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
how did you get the value of 2000N.What calculations are needed to arrive at it
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Good
Berger describes sociologists as concerned with
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