Data relating to change in locus of control orientation of parents overtime (from pre-birth to 20 years later), participating in the Avon Longitudinal Study of Parents and Children (ALSPAC)

Locus of control (LOC) measures an individual׳s expectancy regarding their ability to affect what happens to them based on their behavior. Those with an internal LOC (ILOC) believe their own behavior influences what happens to them. Those with an external LOC (ELOC) perceive that what happens to them is beyond their control (i.e. determined by luck, fate, chance or powerful others) [1]. A vast amount of research (mainly cross-sectional) suggests that an ELOC is associated with many adverse personal, social, academic and health outcomes. LOC data were uniquely collected prenatally from over 12,000 pregnant women and their partners enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). The LOC measure used was a shortened version of the adult version of the Nowicki-Strickland Internal-External locus of control scale. This was administered to the mothers within self-completion questionnaires at three-time points: during pregnancy, at 6 and at 18 years post-partum. In parallel, self-completion questionnaires containing the same LOC questions were completed by their partners during pregnancy, at 6 and 20 years later. ALSPAC LOC data are unique in that they measured orientation over time and on a much larger sample of respondents than is usual. We describe the scale used, why it was chosen and how individual scores changed over time.


a b s t r a c t
Locus of control (LOC) measures an individual's expectancy regarding their ability to affect what happens to them based on their behavior. Those with an internal LOC (ILOC) believe their own behavior influences what happens to them. Those with an external LOC (ELOC) perceive that what happens to them is beyond their control (i.e. determined by luck, fate, chance or powerful others) [1]. A vast amount of research (mainly cross-sectional) suggests that an ELOC is associated with many adverse personal, social, academic and health outcomes.
LOC data were uniquely collected prenatally from over 12,000 pregnant women and their partners enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). The LOC measure used was a shortened version of the adult version of the Nowicki-Strickland Internal-External locus of control scale. This was administered to the mothers within self-completion questionnaires at three-time points: during pregnancy, at 6 and at 18 years post-partum. In parallel, self-completion questionnaires containing the same LOC questions were completed by their partners during pregnancy, at 6 and 20 years later.
Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/dib ALSPAC LOC data are unique in that they measured orientation over time and on a much larger sample of respondents than is usual. We describe the scale used, why it was chosen and how individual scores changed over time. &

Value of the data
The ALSPAC dataset contains information on a large sample of women and their partners in a geographically defined population whose lives were monitored over many years.
The data provide a basis for identification of the antecedents and consequences of possessing a particular locus of control in parents.
The data allow detailed analyses of events and social circumstances over the lifespan and their association with changes in locus of control orientation.
The data allow detailed analyses of the impact of parental locus of control on child and adolescent health and development.

Data
In this paper, we describe adult data on locus of control for men and women over time.
The ALSPAC study website contains details of all the data that are available through a fully searchable data dictionary: 〈http://www.bris.ac.uk/alspac/researchers/our-data/〉. Data can be obtained by bona fide researchers, for a fee, after application to the ALSPAC Executive Committee. Details on how to apply and costs involved are available on the following: (http://www.bristol.ac.uk/ alspac/researchers/access/).

Why is locus of control (LOC) important?
Julian Rotter published the concept of locus of control (LOC) in 1966, and provided a scale with which to measure it. He defined LOC as a generalized problem-solving expectancy [1].
An internal LOC (ILOC) was found to be associated with achievement in many aspects of life and therefore may be related to success in, for example: academia [2][3][4]; business [5,6]; sporting achievement [7][8][9]; as well as being an indicator of psychological adjustment [10][11][12]; and physical health [13][14][15]. An external locus of control (ELOC) in one or both parents can impact negatively on child behavior outcomes and the child's own LOC [e.g. [16][17][18]]. During the last 30 years, the LOC of the general US population appears to have become more external [19] but the reasons for this trend are unknown.

The Avon Longitudinal Study of Parents and Children (ALSPAC)
Data collections in ALSPAC were designed to determine the environmental and genetic factors that are associated with the health and development of the study offspring [20][21][22]. As part of the design there was a concerted effort before the child's birth to obtain from the parents baseline details of their personalities, moods and attitudes, including LOC. ALSPAC recruited 14,541 pregnant women resident in Avon, UK with expected dates of delivery between 1st April 1991 and 31st December 1992 (an estimated 80% of the eligible population). Of these initial pregnancies, there was a total of 14,676 fetuses, resulting in 14,062 live births, 13,988 of whom were alive at 1 year of age. Data were collected at various time-points via self-completion questionnaires, biological samples, hands-on measurements, and linkage to other data sets. For full details of all the data collected see the study website: http://www.bristol.ac.uk/alspac/researchers/our-data/. Ethical approval for the study was obtained from the ALSPAC Ethics and Law Committee [ALEC; IRB00003312] (registered on the Office of Human Research Protections database as UBristol IRB #1) and the Local Research Ethics Committees [23].
The mothers have been followed throughout the life of the study child, but partners were only included in the study with the permission of mothers (i.e. initially they were not enrolled in their own right). Mothers were given a questionnaire which they could hand to their partner if they wished; partners were given their own reply-paid envelope in which to return their completed questionnaires to avoid potential bias and protect the individual's confidentiality.
The three main reasons for loss to follow-up were: when the child died; the mother refused; or moved away and proved untraceable. As with all longitudinal studies, attrition rates increased over time [21,22].

The LOC measure used
The LOC measure used was a shortened version of the Adult Nowicki-Strickland Internal-External locus of control scale (ANSIE) [24]. It was developed by Stephen Nowicki specifically for the ALSPAC study, comprising 12 questions taken from the original 40 question scale. The ANSIE was chosen over Do you think it's better to be clever than to be lucky? 0 1 To create the score, the following questions were coded: Yes¼ 1; No¼ 0: 2, 3, 4, 6, 8, 9,11. The remaining questions were coded as Yes ¼0; No¼ 1: 1, 5, 7, 10, 12.
The responses were then summed. An ELOC was defined as a score greater than the median.
health-related scales because it was a generalized scale consistent with Rotter's definition and would have the potential to relate to a wider range of factors. This version was validated on a sample of 135 pregnant women in the US prior to use in ALSPAC. The 12-question scale (Table 1) was administered to the mothers within self-completion questionnaires at three time points: during pregnancy, and at 6 and 18 years post-partum. In parallel, during pregnancy and at 6 years post-delivery, the mothers were sent self-completion questionnaires for the partners which contained identical LOC questions. Around 20 years after the study child's birth, the partners were invited to a clinic, and they responded to a computerized questionnaire which included identical LOC questions. ELOC was defined as a score greater than the median and ILOC as equal to, or less than, the median.

Responses over time associated with socio-economic factors
For the mothers, the availability of LOC data varied over time in regard to various social, economic and lifestyle features (Table 2a), with a proportional reduction in residents of publicly owned housing, young mothers, partners' manual social class, low levels of maternal education, and smoking as measured in pregnancy. Similar biases were present in their partners (Table 2b); it should be noted that the group answering the LOC questions in the clinic (20 years post-delivery) were also different as they were, of necessity, still resident in or near the study area. The women who answered all three LOC questionnaires were at the more advantaged end of the social spectrum. Nevertheless parents from disadvantaged backgrounds are included in sufficient numbers for sub-group analyses when required.  Table 3. It is important to note that the data shown are subject to the changes in response rates over time. For a true assessment of the individual's trends over time it is important to confine the analyses to individuals who answered at all three time points. In general, an examination of the statistics for the LOC scale show that women have a higher score (i.e. more external) than the partners, whether one examines the means or the medians. 2. Examination of the subgroup of women who answered the external questions at all three time points showed more reliable patterns (Table 4)only two of the external questions showed a difference over time: Q9 increased as the women got older, and Q11 which was at its lowest when the child was 6presumably when the mother felt she was running the householdbut increased again when the child was in late adolescence. Trends of increasing internality were apparent for Q5, Q7, Q10 and Q12. 3. For the women's partners, there was a gradual increase in externality as measured by Q4, but the increase in positive answers to Q9 was similar to that for the women ( Table 4). Trends of increasing internality were again apparent for Q5, Q7, Q10 and Q12. 4. The trends concerning the mean LOC values indicate little change in orientation in the mothers over time, but for the partners, there was an increase in externality when the children were aged six (Table 4).     Table 6 Publications using parental locus of control in ALSPAC.

Authors Outcomes Environment Results
Golding et al. [25] LOC as measured in pregnancy Prenatal parental ILOC is associated with higher child IQ at ages 4 (n¼986). At 8 years (n ¼6801) the IQ was increased by as much as 7 points if the mother was ILOC.
Maternal LOC as measured in pregnancy. Parenting style and investment in early childhood human capital.
Maternal LOC strongly predicts attitudes towards parenting styles and time investment in their child. Gutman et al. [30] Nurturing parenting capability from infancy to early childhood.
Maternal LOC as measured in pregnancy. Individual characteristics of mothers and children; social networks, SES and marital relations of mother; prediction of parenting behaviors types. LOC measures were available for the three-time points for 3829 women. The correlations between the pregnancy measure and that 6 years later was 0.546; that between pregnancy and 18 years later was 0.535; and the correlation between the measures at 6 and 18 years was 0.559. All were highly significant (Po 0.0001). For the men over time, fewer were involved (1244), but the correlation coefficients were very similar (0.548, 0.535 and 0.551).
Although only 959 pairs of the men and women had completed questionnaires at each of the three-time points, the results are clear (Table 5): the LOCs of the women is poorly correlated with the LOCs of their partners (r o0.225).

Acknowledgements
We are extremely grateful to all the families who took part in this study, the midwives for their help in recruiting them, and the whole ALSPAC team, which includes interviewers, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers, receptionists and nurses.

Funding
The UK Medical Research Council and the Wellcome Trust (Grant ref: 102215/2/13/2) and the University of Bristol currently provide core support for ALSPAC. Analyses of the locus of control data was funded by the John Templeton Foundation (58223).
The funders had no involvement in the study design nor in the collection, analysis and interpretation of the data.

Transparency document. Supporting information
Transparency data associated with this article can be found in the online version at https://doi.org/ 10.1016/j.dib.2018.07.014.