La educación inicial

British Cohort Survey

From the BCS 1970 data, children were selected for study if they met the following require- ments: their postcode was recorded at time of interview and available via the Centre for Longitudinal Studies, and the medical examination form, consisting of height and weight, was completed. From 16,135 children, only those in the 1986 sweep (11,622 children) also had available information on postcodes.

Due to the confidentiality agreement between the BCS70 cohort and the CLS which conceals the identity of the individuals, the CLS agreed to provide only the distances between all fast food outlets and each child of the 1986 sweep provided the fast food outlets’ postcodes without revealing further, identifying information. The following procedure was used to collect distances: after obtaining the postcodes for each outlet, the outlet and cohort member postcodes were converted to XY coordinates using postcode directories from UKBORDERS. These directories contain complete versions of current and historical postcode directories as well as a Grid Reference for each postcode. 96% (914) of all outlets and 98% (11,422) of the entire 1986 sample size was coded. Next, Pythagoras’s theorem was used to obtain distances from each individual to all outlets- this provided straight line point A to B distances. The nearest outlet was then identified and distance recorded. The duration of time the children were exposed to the nearest outlet was calculated by taking the difference between the year of the survey (1986 or 1980), and the year the outlet opened.

Although postcodes were not available for the 10-year-old children, locations were assigned to those individuals that remained in their LEA between age 10 and 16. From the 14,940 children of the 1980 sweep, 66% (9,831) remained in their respective LEAs. Since information on weights at age five was not recorded in the 1975 survey, this wave was excluded from the analysis.

From the 11,622 teenagers, 53% (6,143) had complete medical examination forms. The sample of 16 year olds fell to 5,498 after removing the people that had incomplete height or weight responses and did match the individuals with coded postcodes from the pool of 10-year-olds. Of the 9,831 10-year-old children, 81% (8,011) had complete height/weight responses and corresponded with the individuals that had coded postcodes.

Explanatory Variables

The following variables were used from BCS 1980:

Father’s Social Class I use a generated measure of father’s social class in 1980. It is classed into the 5 principal classes (I, II, III (non manual and manual), IV, V (BCS3FCL). The first group is used as the reference category. These are the following categories.

1 Professional occupations.

2 Managerial and technical occupations. 3.1 Skilled occupations (non manual). 3.2 Skilled occupations (manual). 4 Partly skilled occupations. 5 Unskilled occupations.

6 Unclassifiable occupations or occupations with insufficient info/armed forces/carer/unemployed/sick/retired. 7.Missing information.

Mother’s BMI: Constructed from variable e1 2 - mother’s weight in kgs and variable e1 1 - mother’s height in centimetres.

Father’s BMI: Constructed from variable e2 2 - PI - father’s weight in kgs and variable e2 1 - father’s height in centimetres.

Child’s BMI at age 10: Constructed from variable meb19 1 -child’s weight in grams and meb17 - child’s height in millimetres.

The following variables were used from the BCS 1986:

Ethnic group: Variable C6 14 1=European, 2= West Indian, 3=Asian, 4=Other.

Sex: Describes child as being male or female, constructed from variable sex86 where male=1 and female=0.

Smoker: variable gh11 describes whether teen is a smoker (=1) or non-smoker (=0). Survey asked if teenager smokes at all. We recoded the variable so that yes, cigarettes, yes, cigars, pipes, etc means the teen does smoke, and never smoked and no, but ex smoker to

mean the teen does not smoke. Those questions that had responses not sure were coded as missing values.

Household Ownership of Microwave: Variable PG1 22 - Has your household a microwave oven? Yes=1 and No=0.

Land: Variable OA2 1 Teenager’s Country of Birth. 0 if the respondent lives in Eng- land, 1 if the respondent lives in Scotland and 2 if the respondent lives in Wales.

London: 1 if the respondent lives in London, 0 if respondent does not live in London.

Urban: Variable M307: Inner Urban Area: Yes=1 and No=0. Table A.1: Descriptive statistics for the whole sample

Variable Mean SD N

Body Mass Index at age 16 21.255 3.209 4,999 Proportion Obese 0.086 0.2730 4,999 Proportion Overweight 0.217 0.412 4,999 Proportion having a fast food outlet within 5 miles 0.187 0.391 11,621 Proportion having a fast food outlet within 2 miles 0.077 0.266 11,621 Proportion having a fast food outlet within 1 mile 0.026 0.164 11,621 Distance to closest fast food outlet 5.302 11.593 11,621 Duration of closest fast food outlet in 1986 2.543 4.077 11,621 Intensity of fast food exposure 4.513 12.431 11,621 Takeaway per week 1.016 1.255 5,400 Household owns a microwave 0.428 0.495 6,969 BMI at age 10 16.868 2.097 8,520 Mother’s BMI 23.425 3.846 9,250 Father’s BMI 24.491 3.025 8,785 Proportion of smokers 0.106 0.308 10,016

A.1.3 Summary statistics and determinants of BMI

Table A.2: Descriptive statistics - takeaway and school meal consumption

Mean SD N

Eats Burgers 0.382 0.486 11555

Eats Fish and Chips 0.295 0.456 11555

Eats Pizza 0.330 0.470 11555

Eats Indian Takeaway 0.0273 0.163 11555 Eats Chinese Takeaway 0.160 0.367 11555 Lunch Bought Outside 0.109 0.312 11555

Free School Meal 0.0550 0.228 11555

Brought Lunch 0.167 0.373 11555

Went Home For Lunch 0.180 0.385 11555

Table A.3: Density of fast food outlets per LEA and its effect on buying lunch outside of school

Lunch Bought Outside Lunch Bought Outside Average distance to fast food outlet per LEA 0.002∗∗ 0.002∗∗

(0.001) (0.001)

Control Variables _X

Observations 9100 4965

R2 _{0.001 0.020}

Dependent variable is the probability of buying lunch outside of school. The following control variables are included in specification 2: gender, lagged BMI, parental BMI, social class, location, ethnicity, ownership of

microwave, smoking status and birth weight. Standard errors clustered at LEA in parentheses. ∗ p < .10,

∗∗