* First order of business: always open a log:
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name: <unnamed>
log: C:\Users\Michael\Documents\newer web pages\soc_meth_proj3\fall_2016_logs\class1.log
log type: text
opened on: 26 Sep 2016, 10:55:01
. describe
Contains data from C:\Users\Michael\Desktop\cps_mar_2000_new_unchanged.dta
obs: 133,710
vars: 55 1 Feb 2009 13:36
size: 14,574,390
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storage display value
variable name type format label variable label
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year int %8.0g yearlbl Survey year
serial long %12.0g seriallbl
Household serial number
hhwt float %9.0g hhwtlbl Household weight
region byte %27.0g regionlbl
Region and division
statefip byte %57.0g statefiplbl
State (FIPS code)
metro byte %27.0g metrolbl Metropolitan central city status
metarea int %50.0g metarealbl
Metropolitan area
ownershp byte %21.0g ownershplbl
Ownership of dwelling
hhincome long %12.0g hhincomelbl
Total household income
pubhous byte %8.0g pubhouslbl
Living in public housing
foodstmp byte %8.0g foodstmplbl
Food stamp recipiency
pernum byte %8.0g pernumlbl
Person number in sample unit
perwt float %9.0g perwtlbl Person weight
momloc byte %8.0g momloclbl
Mother's location in the household
poploc byte %8.0g poploclbl
Father's location in the household
sploc byte %8.0g sploclbl Spouse's location in household
famsize byte %25.0g famsizelbl
Number of own family members in hh
nchild byte %18.0g nchildlbl
Number of own children in household
nchlt5 byte %23.0g nchlt5lbl
Number of own children under age 5 in hh
nsibs byte %18.0g nsibslbl Number of own siblings in household
relate int %34.0g relatelbl
Relationship to household head
age byte %19.0g agelbl Age
sex byte %8.0g sexlbl Sex
race int %37.0g racelbl Race
marst byte %23.0g marstlbl Marital status
popstat byte %14.0g popstatlbl
Adult civilian, armed forces, or child
bpl long %27.0g bpllbl Birthplace
yrimmig int %11.0g yrimmiglbl
Year of immigration
citizen byte %31.0g citizenlbl
Citizenship status
mbpl long %27.0g mbpllbl Mother's birthplace
fbpl long %27.0g fbpllbl Father's birthplace
hispan int %29.0g hispanlbl
Hispanic origin
educ99 byte %38.0g educ99lbl
Educational attainment, 1990
educrec byte %23.0g educreclbl
Educational attainment recode
schlcoll byte %45.0g schlcolllbl
School or college attendance
empstat byte %30.0g empstatlbl
Employment status
occ1990 int %78.0g occ1990lbl
Occupation, 1990 basis
wkswork1 byte %8.0g wkswork1lbl
Weeks worked last year
hrswork byte %8.0g hrsworklbl
Hours worked last week
uhrswork byte %13.0g uhrsworklbl
Usual hours worked per week (last yr)
hourwage int %8.0g hourwagelbl
Hourly wage
union byte %33.0g unionlbl Union membership
inctot long %12.0g Total personal income
incwage long %12.0g Wage and salary income
incss long %12.0g Social Security income
incwelfr long %12.0g Welfare (public assistance) income
vetstat byte %10.0g vetstatlbl
Veteran status
vetlast byte %26.0g vetlastlbl
Veteran's most recent period of service
disabwrk byte %34.0g disabwrklbl
Work disability
health byte %9.0g healthlbl
Health status
inclugh byte %8.0g inclughlbl
Included in employer group health plan
last year
himcaid byte %8.0g himcaidlbl
Covered by Medicaid last year
ftotval double %10.0g ftotvallbl
Total family income
perwt_rounded float %9.0g integer perwt, negative values recoded to
0
yrsed float %9.0g based on educrec
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Sorted by: sex
Note: dataset has changed since last saved
* We will have more to say about storage types and labels as the class goes on.
. tabulate race
Race | Freq. Percent Cum.
--------------------------------------+-----------------------------------
White | 113,475 84.87 84.87
Black/Negro | 13,626 10.19 95.06
American Indian/Aleut/Eskimo | 1,894 1.42 96.47
Asian or Pacific Islander | 4,715 3.53 100.00
--------------------------------------+-----------------------------------
Total | 133,710 100.00
. tabulate race [fweight=perwt_rounded]
Race | Freq. Percent Cum.
--------------------------------------+-----------------------------------
White |224,806,952 82.02 82.02
Black/Negro | 35,508,668 12.96 94.98
American Indian/Aleut/Eskimo | 2,847,473 1.04 96.01
Asian or Pacific Islander | 10,924,728 3.99 100.00
--------------------------------------+-----------------------------------
Total |274,087,821 100.00
*key things to note here: the CPS sample we will be using has 133,710 subjects. The sample universe of Americans living in households in March, 2000 was 274 million. The average weight is slightly over 2,000. Undersampled groups like blacks have higher than average weights, so they have a higher percentage in the weighted than the unweighted data.
. summarize perwt_rounded
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
perwt_roun~d | 133710 2049.868 1083.244 93 14281
. tabulate race
Race | Freq. Percent Cum.
--------------------------------------+-----------------------------------
White | 113,475 84.87 84.87
Black/Negro | 13,626 10.19 95.06
American Indian/Aleut/Eskimo | 1,894 1.42 96.47
Asian or Pacific Islander | 4,715 3.53 100.00
--------------------------------------+-----------------------------------
Total | 133,710 100.00
. tabulate race, nolab
Race | Freq. Percent Cum.
------------+-----------------------------------
100 | 113,475 84.87 84.87
200 | 13,626 10.19 95.06
300 | 1,894 1.42 96.47
650 | 4,715 3.53 100.00
------------+-----------------------------------
Total | 133,710 100.00
* Note that all variables, including categorical variables, are stored as numbers. White=100 in the CPS race variable. Numbers take up less space and are easier to compare, but that means we will have to keep numbers and value labels both in mind.
. summarize incwage
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
incwage | 103226 19462.59 28843.38 0 364302
. summarize inctot
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
inctot | 103226 26011.4 32061.48 -24998 425510
. tabulate incwage
Wage and |
salary |
income | Freq. Percent Cum.
------------+-----------------------------------
0 | 35,825 34.71 34.71
1 | 7 0.01 34.71
5 | 15 0.01 34.73
7 | 1 0.00 34.73
8 | 1 0.00 34.73
10 | 1 0.00 34.73
12 | 2 0.00 34.73
18 | 1 0.00 34.73
20 | 10 0.01 34.74
21 | 2 0.00 34.74
28 | 2 0.00 34.75
30 | 5 0.00 34.75
31 | 1 0.00 34.75
34 | 4 0.00 34.76
35 | 5 0.00 34.76
36 | 1 0.00 34.76
40 | 8 0.01 34.77
44 | 1 0.00 34.77
45 | 4 0.00 34.77
46 | 3 0.00 34.78
--Break--
r(1);
* Stata command summarize is for variables where the average of the numbers makes sense. Tabulate is for categorical variables. Just like you never want to summarize race (because the numbers don’t mean anything, so averaging together doesn’t mean anything), similarly you don’t want to tabulate incwage, because you just get a list of every different income that anyone reported. The output would be like the phone book if we didn’t interrupt the command.
. summarize age
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
age | 133710 35.17964 22.21722 0 90
* Note the age topcode of 90. See the ipums documentation for topcodes, sample universes, and so on.
. summarize yrsed
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
yrsed | 103226 12.77328 3.156011 0 17
. tabulate age if yrsed==.
Age | Freq. Percent Cum.
--------------------+-----------------------------------
Under 1 year | 1,713 5.62 5.62
1 | 1,932 6.34 11.96
2 | 1,950 6.40 18.35
3 | 1,939 6.36 24.71
4 | 1,965 6.45 31.16
5 | 1,998 6.55 37.71
6 | 2,059 6.75 44.47
7 | 2,176 7.14 51.61
8 | 2,163 7.10 58.70
9 | 2,243 7.36 66.06
10 | 2,202 7.22 73.28
11 | 2,083 6.83 80.12
12 | 2,035 6.68 86.79
13 | 2,047 6.71 93.51
14 | 1,979 6.49 100.00
--------------------+-----------------------------------
Total | 30,484 100.00
* The period, or “.” Is the code for missing value in Stata. People under 15 had missing education, because the question was not asked of them (see the Ipums documentation).
. sort sex
. by sex: summarize yrsed if age>=25 & age<=34
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-> sex = Male
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
yrsed | 9027 13.31212 2.967666 0 17
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-> sex = Female
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
yrsed | 9511 13.55657 2.854472 0 17
* We asked the question, is this 0.24 years of education difference a significant difference? The first way to think about the question is with relation to the CPS data itself, in which there are no unknowns, we know that 13.55>13.31. The more complicated question is about the US. Does the difference between 13.55 and 13.31 in the CPS lead us to reject the null hypothesis that men and women in the US have the same level of education? Even though the 0.24 years of education difference is small, the ttest below demonstrates very definitively that the difference is statistically significant. In other words, the difference between 13.55 and 13.31 is large enough (and the 18,000 subjects in CPS who are involved in this sample are numerous enough) to allow us to be sure that men and women in the US age 25-34 did not have the same mean educational attainment.
. ttest yrsed if age>=25 & age<=34, by(sex)
Two-sample t test with equal variances
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Group | Obs Mean Std. Err. Std. Dev. [95% Conf. Interval]
---------+--------------------------------------------------------------------
Male | 9027 13.31212 .0312351 2.967666 13.25089 13.37335
Female | 9511 13.55657 .0292693 2.854472 13.49919 13.61394
---------+--------------------------------------------------------------------
combined | 18538 13.43753 .0213921 2.912627 13.3956 13.47946
---------+--------------------------------------------------------------------
diff | -.2444469 .0427623 -.3282649 -.1606289
------------------------------------------------------------------------------
diff = mean(Male) - mean(Female) t = -5.7164
Ho: diff = 0 degrees of freedom = 18536
Ha: diff < 0 Ha: diff != 0 Ha: diff > 0
Pr(T < t) = 0.0000 Pr(|T| > |t|) = 0.0000 Pr(T > t) = 1.0000
. log close
name: <unnamed>
log: C:\Users\Michael\Documents\newer web pages\soc_meth_proj3\fall_2016_logs\c
> lass1.log
log type: text
closed on: 26 Sep 2016, 12:55:07
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