Appendix 7: Continuous Month Scheme and Crosswalk

Introduction
Continuous Month Crosswalk
Continuous Week Crosswalk

As described in Appendix 6, the various event history arrays present month-by-month or week-by-week information on the respondent's status with respect to various activities. Information about program participation, marriage, and schooling is provided on a monthly basis using a continuous month timeline. Employment histories are presented on a weekly basis using a continuous week timeline. This appendix explains the continuous month/week system and provides the actual dates corresponding to the numbered weeks and months.

Continuous Month Timeline
The non-employment event history arrays are presented using two different timelines. The first, a continuous month approach, labels January 1980 as month 1, February 1980 as month 2, and so on. Thus, a respondent born in month 4 might start receiving public assistance in month 193 and leave the program in month 198. Key events occurring during the life of each cohort member can be indexed within this month-by-month structure. To aid users, a number of variables other than the event history arrays have already been created using the event history format. For example, the month of the respondent's birth and the month of the respondent's interview are both presented in continuous month format. Second, the event history arrays can be constructed using actual month and year dates. Using this approach, the same respondent, born in April 1980, started receiving public assistance in January 1997 and left the program in June 1997.

The data set includes variables for the event history arrays for every month number under the continuous month scheme. However, actual month and year dates are only included for a given respondent in months in which transitions occurred. That is, the respondent in the example above would have continuous month variables relating to program participation status for every month beginning with 172 (the month of the respondent's 14^th birthday) but would only have actual date variables for January and June 1997. To aid users in moving between the two dating schemes, table 1 in this appendix contains a crosswalk between actual dates and continuous month numbers.

The continuous month system allows researchers to easily compare the times at which various events occurred in the youth's life. The following example illustrates a case in which a youth turns 17 in February 1997 and, in the same month (month 194 in the continuous timeline), begins receiving AFDC. She remains on AFDC for 2 months (month 194 and month 195). The following table illustrates this information using a month-by-month timeline.

Non-Employment Event History Array Incorporating the Month-by-Month Timeline

Question Name	Participation Status	Month Number (created by the user)	Birth date: CV_CHILD_BIRTH_MONTH
AFDC_STATUS_1997.01	0	193
AFDC_STATUS_1997.02	1	194	194
AFDC_STATUS_1997.03	1	195
AFDC_STATUS_1997.04	0	196

In addition linking the dates through the crosswalk, any user who selects an event array will be able to extract from the data set additional characteristics that relate to that event. The following table presents the additional information that a user may chose to link to the non-employment event history arrays. A user is able to create these and other variable combinations for any status array.

Status	Variable 1	Variable 2	Variable 3
Enrollment	Highest grade attended	Highest grade completed	Highest degree earned
Cohabitation/Marital	Partner's race	Partner's religion	Partner's grade level
AFDC	Received during month	Benefit amount	People benefiting

Continuous Week Timeline
In the event history section of the data set, an employment history of the number of weeks worked is presented in a continuous week-by-week status array. This array is very similar to the month-by-month scheme used for the rest of the event history variables. In this format, the first week of January 1980 is numbered week 1, the second week of January 1980 is numbered week 2, and so on; weeks are listed by exact date as well. This week-by-week array lists each respondent's employment status for each week since the month of the respondent's 14^th birthday.

As with the month-by-month arrays, respondents have data available for every week in the continuous week arrays but only for transition weeks in the actual date arrays. However, users should note that, due to technical considerations, the variable titles in the data number weeks by calendar year rather than from week 1 through week 992. For example, a variable might read "1994 Employment: Employment Status in Week 07" instead of "Employment: Employment Status in Week 737." Table 2 in this appendix provides a crosswalk between the actual beginning date of each week, the continuous week number, and the week number for each week in a calendar year. This table begins with January 1994 because this is the first month in which any NLSY97 respondent could have reached age 14, the youngest age for which the employment event history variables were created. Users who need to see earlier continuous week numbers should contact NLS User Services.

Naming Conventions
The question names of the NLSY97 event history variables incorporate the dates to which the variables apply. The marital status and program participation array titles include the month and year (e.g., AFDC_AMT_1997.12 corresponds to December 1997). Likewise, employment array variables are listed for each week and year (e.g., EMP_STATUS_1997.52 corresponds to the 52^nd week in 1997). The schooling variables are yearly and employ a slightly different system. In general, these variables refer to the school year rather than the calendar year. That is, 1991 in a variable title or in the data for a variable generally indicates the school year starting in fall 1991 and ending in spring 1992.

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Table 1. Continuous Month Crosswalk

Month and year	Continuous month number	Month and year	Continuous month number
January 1980	1	July 1983	43
February 1980	2	August 1983	44
March 1980	3	September 1983	45
April 1980	4	October 1983	46
May 1980	5	November 1983	47
June 1980	6	December 1983	48
July 1980	7	January 1984	49
August 1980	8	February 1984	50
September 1980	9	March 1984	51
October 1980	10	April 1984	52
November 1980	11	May 1984	53
December 1980	12	June 1984	54
January 1981	13	July 1984	55
February 1981	14	August 1984	56
March 1981	15	September 1984	57
April 1981	16	October 1984	58
May 1981	17	November 1984	59
June 1981	18	December 1984	60
July 1981	19	January 1985	61
August 1981	20	February 1985	62
September 1981	21	March 1985	63
October 1981	22	April 1985	64
November 1981	23	May 1985	65
December 1981	24	June 1985	66
January 1982	25	July 1985	67
February 1982	26	August 1985	68
March 1982	27	September 1985	69
April 1982	28	October 1985	70
May 1982	29	November 1985	71
June 1982	30	December 1985	72
July 1982	31	January 1986	73
August 1982	32	February 1986	74
September 1982	33	March 1986	75
October 1982	34	April 1986	76
November 1982	35	May 1986	77
December 1982	36	June 1986	78
January 1983	37	July 1986	79
February 1983	38	August 1986	80
March 1983	39	September 1986	81
April 1983	40	October 1986	82
May 1983	41	November 1986	83
June 1983	42	December 1986	84

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Month and year	Continuous month number	Month and year	Continuous month number
January 1987	85	July 1990	127
February 1987	86	August 1990	128
March 1987	87	September 1990	129
April 1987	88	October 1990	130
May 1987	89	November 1990	131
June 1987	90	December 1990	132
July 1987	91	January 1991	133
August 1987	92	February 1991	134
September 1987	93	March 1991	135
October 1987	94	April 1991	136
November 1987	95	May 1991	137
December 1987	96	June 1991	138
January 1988	97	July 1991	139
February 1988	98	August 1991	140
March 1988	99	September 1991	141
April 1988	100	October 1991	142
May 1988	101	November 1991	143
June 1988	102	December 1991	144
July 1988	103	January 1992	145
August 1988	104	February 1992	146
September 1988	105	March 1992	147
October 1988	106	April 1992	148
November 1988	107	May 1992	149
December 1988	108	June 1992	150
January 1989	109	July 1992	151
February 1989	110	August 1992	152
March 1989	111	September 1992	153
April 1989	112	October 1992	154
May 1989	113	November 1992	155
June 1989	114	December 1992	156
July 1989	115	January 1993	157
August 1989	116	February 1993	158
September 1989	117	March 1993	159
October 1989	118	April 1993	160
November 1989	119	May 1993	161
December 1989	120	June 1993	162
January 1990	121	July 1993	163
February 1990	122	August 1993	164
March 1990	123	September 1993	165
April 1990	124	October 1993	166
May 1990	125	November 1993	167
June 1990	126	December 1993	168

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Month and year	Continuous month number	Month and year	Continuous month number
January 1994	169	August 1997	212
February 1994	170	September 1997	213
March 1994	171	October 1997	214
April 1994	172	November 1997	215
May 1994	173	December 1997	216
June 1994	174	January 1998	217
July 1994	175	February 1998	218
August 1994	176	March 1998	219
September 1994	177	April 1998	220
October 1994	178	May 1998	221
November 1994	179	June 1998	222
December 1994	180	July 1998	223
January 1995	181	August 1998	224
February 1995	182	September 1998	225
March 1995	183	October 1998	226
April 1995	184	November 1998	227
May 1995	185	December 1998	228
June 1995	186	January 1999	229
July 1995	187	February 1999	230
August 1995	188	March 1999	231
September 1995	189	April 1999	232
October 1995	190	May 1999	233
November 1995	191	June 1999	234
December 1995	192	July 1999	235
January 1996	193	August 1999	236
February 1996	194	September 1999	237
March 1996	195	October 1999	238
April 1996	196	November 1999	239
May 1996	197	December 1999	240
June 1996	198	January 2000	241
July 1996	199	February 2000	242
August 1996	200	March 2000	243
September 1996	201	April 2000	244
October 1996	202	May 2000	245
November 1996	203	June 2000	246
December 1996	204	July 2000	247
January 1997	205	August 2000	248
February 1997	206	September 2000	249
March 1997	207	October 2000	250
April 1997	208	November 2000	251
May 1997	209	December 2000	252
June 1997	210	January 2001	253
July 1997	211	February 2001	254

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Month and year	Continuous month number	Month and year	Continuous month number
March 2001	255	February 2002	266
April 2001	256	March 2002	267
May 2001	257	April 2002	268
June 2001	258	May 2002	269
July 2001	259	June 2002	270
August 2001	260	July 2002	271
September 2001	261	August 2002	272
October 2001	262	September 2002	273
November 2001	263	October 2002	274
December 2001	264	November 2002	275
January 2002	265	December 2002	276

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Table 2. Continuous Week Crosswalk

Week start date	Continuous week number	Calendar year week number	Week start date	Continuous week number	Calendar year week number
12/26/1993	731	1	10/30/1994	775	45
01/02/1994	732	2	11/06/1994	776	46
01/09/1994	733	3	11/13/1994	777	47
01/16/1994	734	4	11/20/1994	778	48
01/23/1994	735	5	11/27/1994	779	49
01/30/1994	736	6	12/04/1994	780	50
02/06/1994	737	7	12/11/1994	781	51
02/13/1994	738	8	12/18/1994	782	52
02/20/1994	739	9	12/25/1994	783	53
02/27/1994	740	10	01/01/1995	784	1
03/06/1994	741	11	01/08/1995	785	2
03/13/1994	742	12	01/15/1995	786	3
03/20/1994	743	13	01/22/1995	787	4
03/27/1994	744	14	01/29/1995	788	5
04/03/1994	745	15	02/05/1995	789	6
04/10/1994	746	16	02/12/1995	790	7
04/17/1994	747	17	02/19/1995	791	8
04/24/1994	748	18	02/26/1995	792	9
05/01/1994	749	19	03/05/1995	793	10
05/08/1994	750	20	03/12/1995	794	11
05/15/1994	751	21	03/19/1995	795	12
05/22/1994	752	22	03/26/1995	796	13
05/29/1994	753	23	04/02/1995	797	14
06/05/1994	754	24	04/09/1995	798	15
06/12/1994	755	25	04/16/1995	799	16
06/19/1994	756	26	04/23/1995	800	17
06/26/1994	757	27	04/30/1995	801	18
07/03/1994	758	28	05/07/1995	802	19
07/10/1994	759	29	05/14/1995	803	20
07/17/1994	760	30	05/21/1995	804	21
07/24/1994	761	31	05/28/1995	805	22
07/31/1994	762	32	06/04/1995	806	23
08/07/1994	763	33	06/11/1995	807	24
08/14/1994	764	34	06/18/1995	808	25
08/21/1994	765	35	06/25/1995	809	26
08/28/1994	766	36	07/02/1995	810	27
09/04/1994	767	37	07/09/1995	811	28
09/11/1994	768	38	07/16/1995	812	29
09/18/1994	769	39	07/23/1995	813	30
09/25/1994	770	40	07/30/1995	814	31
10/02/1994	771	41	08/06/1995	815	32
10/09/1994	772	42	08/13/1995	816	33
10/16/1994	773	43	08/20/1995	817	34
10/23/1994	774	44	08/27/1995	818	35

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Week start date	Continuous week number	Calendar year week number	Week start date	Continuous week number	Calendar year week number
09/03/1995	819	36	07/07/1996	863	28
09/10/1995	820	37	07/14/1996	864	29
09/17/1995	821	38	07/21/1996	865	30
09/24/1995	822	39	07/28/1996	866	31
10/01/1995	823	40	08/04/1996	867	32
10/08/1995	824	41	08/11/1996	868	33
10/15/1995	825	42	08/18/1996	869	34
10/22/1995	826	43	08/25/1996	870	35
10/29/1995	827	44	09/01/1996	871	36
11/05/1995	828	45	09/08/1996	872	37
11/12/1995	829	46	09/15/1996	873	38
11/19/1995	830	47	09/22/1996	874	39
11/26/1995	831	48	09/29/1996	875	40
12/03/1995	832	49	10/06/1996	876	41
12/10/1995	833	50	10/13/1996	877	42
12/17/1995	834	51	10/20/1996	878	43
12/24/1995	835	52	10/27/1996	879	44
12/31/1995	836	1	11/03/1996	880	45
01/07/1996	837	2	11/10/1996	881	46
01/14/1996	838	3	11/17/1996	882	47
01/21/1996	839	4	11/24/1996	883	48
01/28/1996	840	5	12/01/1996	884	49
02/04/1996	841	6	12/08/1996	885	50
02/11/1996	842	7	12/15/1996	886	51
02/18/1996	843	8	12/22/1996	887	52
02/25/1996	844	9	12/29/1996	888	1
03/03/1996	845	10	01/05/1997	889	2
03/10/1996	846	11	01/12/1997	890	3
03/17/1996	847	12	01/19/1997	891	4
03/24/1996	848	13	01/26/1997	892	5
03/31/1996	849	14	02/02/1997	893	6
04/07/1996	850	15	02/09/1997	894	7
04/14/1996	851	16	02/16/1997	895	8
04/21/1996	852	17	02/23/1997	896	9
04/28/1996	853	18	03/02/1997	897	10
05/05/1996	854	19	03/09/1997	898	11
05/12/1996	855	20	03/16/1997	899	12
05/19/1996	856	21	03/23/1997	900	13
05/26/1996	857	22	03/30/1997	901	14
06/02/1996	858	23	04/06/1997	902	15
06/09/1996	859	24	04/13/1997	903	16
06/16/1996	860	25	04/20/1997	904	17
06/23/1996	861	26	04/27/1997	905	18
06/30/1996	862	27	05/04/1997	906	19

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Week start date	Continuous week number	Calendar year week number	Week start date	Continuous week number	Calendar year week number
05/11/1997	907	20	03/08/1998	950	11
05/18/1997	908	21	03/15/1998	951	12
05/25/1997	909	22	03/22/1998	952	13
06/01/1997	910	23	03/29/1998	953	14
06/08/1997	911	24	04/05/1998	954	15
06/15/1997	912	25	04/12/1998	955	16
06/22/1997	913	26	04/19/1998	956	17
06/29/1997	914	27	04/26/1998	957	18
07/06/1997	915	28	05/03/1998	958	19
07/13/1997	916	29	05/10/1998	959	20
07/20/1997	917	30	05/17/1998	960	21
07/27/1997	918	31	05/24/1998	961	22
08/03/1997	919	32	05/31/1998	962	23
08/10/1997	920	33	06/07/1998	963	24
08/17/1997	921	34	06/14/1998	964	25
08/24/1997	922	35	06/21/1998	965	26
08/31/1997	923	36	06/28/1998	966	27
09/07/1997	924	37	07/05/1998	967	28
09/14/1997	925	38	07/12/1998	968	29
09/21/1997	926	39	07/19/1998	969	30
09/28/1997	927	40	07/26/1998	970	31
10/05/1997	928	41	08/02/1998	971	32
10/12/1997	929	42	08/09/1998	972	33
10/19/1997	930	43	08/16/1998	973	34
10/26/1997	931	44	08/23/1998	974	35
11/02/1997	932	45	08/30/1998	975	36
11/09/1997	933	46	09/06/1998	976	37
11/16/1997	934	47	09/13/1998	977	38
11/23/1997	935	48	09/20/1998	978	39
11/30/1997	936	49	09/27/1998	979	40
12/07/1997	937	50	10/04/1998	980	41
12/14/1997	938	51	10/11/1998	981	42
12/21/1997	939	52	10/18/1998	982	43
12/28/1997	940	1	10/25/1998	983	44
01/04/1998	941	2	11/01/1998	984	45
01/11/1998	942	3	11/08/1998	985	46
01/18/1998	943	4	11/15/1998	986	47
01/25/1998	944	5	11/22/1998	987	48
02/01/1998	945	6	11/29/1998	988	49
02/08/1998	946	7	12/06/1998	989	50
02/15/1998	947	8	12/13/1998	990	51
02/22/1998	948	9	12/20/1998	991	52
03/01/1998	949	10	12/27/1998	992	1

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Week start date	Continuous week number	Calendar year week number	Week start date	Continuous week number	Calendar year week number
1/3/1999	993	2	11/7/1999	1037	46
1/10/1999	994	3	11/14/1999	1038	47
1/17/1999	995	4	11/21/1999	1039	48
1/24/1999	996	5	11/28/1999	1040	49
1/31/1999	997	6	12/5/1999	1041	50
2/7/1999	998	7	12/12/1999	1042	51
2/14/1999	999	8	12/19/1999	1043	52
2/21/1999	1000	9	12/26/1999	1044	53
2/28/1999	1001	10	1/2/2000	1045	1
3/7/1999<