G1 Parenting variables

Data on G1 parenting practices were collected from the mothers of G2 children at ages four and eight years. Mothers were asked more than 20 questions on a range of topics related to cognitive stimulation, discipline style and parental interest in school activities (table 7.2). Similar age-appropriate questions were asked at ages four and eight years. For example, identical questions about the type of parent-child affection were asked at both ages. At age four parents were asked about their teaching of basic school skills (e.g. the alphabet) prior to starting primary education, whereas at age eight these skills were no longer relevant and questions focused on the degree of stimulation provided by the reading culture in the home, which was more likely to contribute to their cognitive development.

In order to form coherent subsets between questionnaire items that were highly correlated (for example, parents taught their child the alphabet; parents taught their child to write), factor analysis was employed to maximise the information available at each age while reducing the number of variables into factors. Each factor score represents a continuum along which individuals vary and can be used in subsequent regression analyses. Components of each factor can be summed to yield an ordinal scale representing the relative position of individuals on that scale. Factor analysis has previously been used to define parent-child relationships by identifying factors corresponding to parental involvement in their child’s schooling (Garcia Bacete & Oliver Rodriguez, 2004) and the family learning environment (Marjoribanks, 2001; Marjoribanks, 2003) in a cohort of Australian families, as well as authoritative, authoritarian and permissive parenting typologies (Robinson et al., 1995).

Table 7.2 Questions relating to G1 parenting practices.

Table 7.2 Questions relating to G1 parenting practices. Respondents were G1 mothers or the wives of G1 fathers when G2 offspring were aged four and eight. Responses were binary (Yes/No) unless otherwise stated.

Question Age 4 Age 8

Have you (or your husband) taught X the alphabet? ▪

Have you (or your husband) taught X to count? ▪

Have you (or your husband) taught X to write? ▪

Have you (or your husband) taught X his/her colours? ▪

Have you tried to prepare X in any way for going to school? ▪

Does your husband read or tell stories to X? ▪

Do you read or tell stories to X? ▪

Do you regularly take out books from the library? ▪

Does your husband regularly take out books from the library? ▪

Do you or your husband read for pleasure? ▪

Does X use a lending library of any sort at all? ▪

Does X regularly take out books from the public library? ▪

Does X regularly take out books from the school library? ▪

Does X read for pleasure? ▪

When X has been naughty do you ever send X out of the room or up to bed? ▪ ▪ When X has been naughty do you ever keep X indoors or make X sit still? ▪ ▪

When X has been naughty do you ever smack X? ▪ ▪

When X has been naughty do you ever stop X sweets or not allow X to do something he/she enjoys? ▪ ▪ When X has been naughty do you ever tell X you won’t love them if he/she behaves like that? ▪ ▪ When X has been naughty do you ever say that you will send him/her away or that you’ll have to go away? ▪ ▪ When X has been naughty do you ever try to frighten X with something like a policeman? ▪ ▪ When X has been naughty do you ever threaten to use a stick or something like that? ▪ ▪ Do you and your husband generally agree about dealing with X when he/she is naughty? a ▪ ▪ On the whole, do you feel that where discipline is concerned that you are consistent? b

If X has been especially good during the day, do you generally like to let X know? ▪ If you want X to be good on a particular occasion do you ever promise him/her anything in advance? ▪

Do you or your husband show affection towards X or are you fairly reserved? ▪ ▪ Have you met X’s class teacher or head teacher during the past year? c ▪ Do you ever discuss X’s progress with the class teacher or head teacher? c ▪ At what age would you like X to leave school? d

a

Item dichotomised to ‘Usually agree’ vs. ‘Rarely agree’ and ‘Never agree’.

b

Item dichotomised to ‘absolutely consistent’ and ‘fairly consistent’ vs. ‘not very consistent’.

c

Responses: Yes, with class teacher; with head teacher; with both.

d

Responses: 15 years, 16 years, 17 years, 18 years or later.

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7.2.5.1 Factor analysis

Factor analysis is a method of investigating whether or not a number of variables of interest are linearly related to a smaller number of unobservable factors. This is achieved by transforming variables that correlate with one another into a new set of uncorrelated components (called factors) using a correlation matrix (Jolliffe, 2002). Since the questionnaire items related to parenting were predominantly dichotomous, a tetrachoric correlation was applied as opposed to the more frequently-used Pearson correlation. The tetrachoric correlation between two dichotomous items estimates the Pearson correlation one would obtain if the two constructs were measured continuously. Tetrachoric correlations have been made use of by previous researchers to account for dichotomous responses to questions on symptoms of psychosis (McGorry, et al., 1998) and cannabis-related problems (Copeland, et al., 2005). The resulting matrix is adopted as the starting point for factor analysis.

In factor analysis, the first factor identified will have maximal contribution to the common variance of the observed variables; the second will have maximal contribution subject to being uncorrelated to the first, and so on. A more interpretable solution is often achieved by a process of factor rotation. There are a number of different types of rotations that can be performed after the initial extraction of factors, including orthogonal rotations, such as varimax, which impose the restriction that the factors cannot be correlated, and oblique rotations, such as promax, which allow the factors to be correlated with one another. In these analyses the varimax rotation, which is favoured for simplicity, was used.

The resulting factor loadings, shown in table 7.3 represent how the variables are weighted for each factor. Individual items were retained if they had a loading near or over 0.35 (Jolliffe, 2002). The number of factors to be retained was decided by applying two standard statistical and visual tools commonly used in factor analysis.

i. Factors with eigenvalues smaller than one were excluded since factors retained in this way account for more variance than the average for the variables. This is known as the Kaiser rule (Jolliffe, 2002).

ii. An examination of the plot of the eigenvalues against the corresponding factor numbers, known as the scree plot (figure 7.2). The plot looks like the side of a mountain, and ‘scree’ refers to the debris that has fallen from the mountain and lying at its base. The rate of decline tends to be rapid for the

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first few factors but then levels off. The point at which this occurs is often called the ‘elbow’ and is considered to indicate the maximum number of factors to extract.

In light of previous research (reviewed in chapter 2), questionnaire items representing aspects of parenting purportedly related to offspring cognitive development, such as parental teaching or assisting in school-related learning activities and harsh discipline, were included in the factor analysis. Using these items, a four-factor solution was the clearest and most readily interpretable and accounted for approximately 70% of the total variance in the observed variables (table 7.3). Extracted factors were unique in that few parenting variables loaded substantially on to more than one factor. Furthermore, the internal consistencies of the four factor scores were acceptable with values of Cronbach’s alpha ranging from 0.6 to 0.7. This means that the questionnaire items making up each factor should all measure the same thing (Cronbach, 1951).

7.2.5.2 Intellectual environment

The first factor, labelled ‘intellectual environment’, was composed of questionnaire items representing the reading culture in the homes of G2 offspring when they were aged eight, including the reading habits of their G1 parents and frequency of visits to the library. This factor accounted for 45% of the total variance. Whether or not children read for pleasure did not load strongly onto this factor. Data on intellectual environment were available for 80% (1,349/1,690) of parent-offspring pairs.

7.2.5.3 Coercive discipline

Factor 2 included items relating to parental use of threats and coercion to achieve favourable behaviour, and was labelled ‘coercive discipline’. Items related to threats of being sent away, promises of reward for good behaviour and practices that involved withdrawing privileges or making the child sit still did not load strongly onto this factor and were therefore excluded from the factor analysis. Likewise, the use of corporal punishment (Do you ever smack X?) did not load strongly onto any of the factors and was therefore used separately as a measure of punitive discipline. Data on coercive discipline were available for 76% (1,290/1,690) of parent-offspring pairs.

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7.2.5.4 Affection

The third factor represented items relating to levels of G1 parental affection shown towards G2 offspring when they were aged four and eight years by their parents. Data on affection were available for 79% (1,338/1,690) of parent-offspring pairs.

7.2.5.5 Cognitive stimulation

Factor 4 – labelled ‘cognitive stimulation’ – identified items representing direct measures taken by parents to stimulate or teach their children. This factor therefore contrasts G1 parents who taught their children school-related skills prior to starting formal education with those parents who did not. This factor accounted for the remaining 7% of the total variance in the original data. Many parents taught their children the alphabet or colours by means of a game and therefore items in this factor are likely to represent activities in which there was positive and reciprocal involvement between parents and their offspring. Attempts by parents to prepare their child for school, and parents reading stories to their children, did not load strongly onto this factor. Data on cognitive stimulation were available for 94% (1,592/1,690) of parent-offspring pairs.

Since the extracted factor scores were continuous measures but did not meet the assumptions of normality required for linear regression, 5-point scores were calculated for each of the four extracted factors to produce a minimum score of 0 (parents did not answer ‘yes’ to any of the questions making up that factor) and a maximum score of 4 (parents answered ‘yes’ to all of the questions making up that factor). For the coercive discipline factor, a maximum score of 9 could be assigned but since only 30 parents applied all or most of the discipline practices making up this measure, those with scores of 5 to 9 were recategorised to form a score with a maximum of 4. These additive scales were normally distributed (kurtosis approximately 3; skewness approximately 1) and could therefore be used in regression analyses representing a continuum along which parenting differed with low levels (0) at one end and high levels (4) at the other.

In addition to the measures of G1 parenting derived from factor analysis, three other variables that did not load strongly onto any of the factors were also included in the analyses – parental interest in education, parental aspirations for future educational achievement and corporal punishment.

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Table 7.3 Factor loadings, eigenvalues and cumulative variance for factor pattern of G1

parenting practices.

G1 Parenting practices (n=1,309) Factor 1 Factor 2 Factor 3 Factor 4

Intellectual environment

Mother regularly took books out of the library (age 8) 0.91 Father regularly took books out of the library (age 8) 0.84

Parents read for pleasure (age 8) 0.79

Child regularly took books out of the library (age 8) 0.75

Coercive discipline

Parents told child they wouldn't love him/her (age 8) 0.77

Parents disagreed about discipline practices (age 8) 0.59

Parents told child they wouldn't love him/her (age 4) 0.57

Parents used discipline inconsistently (age 8) 0.56

Parents disagreed about discipline practices (age 4) 0.49

Parents threatened to call a policeman (age 8) 0.48

Parents threatened to call a policeman (age 4) 0.43

Parents threatened to use a stick (age 4) 0.38

Parents threatened to use a stick (age 8) 0.33

Affection

Father was affectionate towards child (age 4) 0.82

Mother was affectionate towards child (age 8) 0.77

Mother was affectionate towards child (age 4) 0.70

Father was affectionate towards child (age 8) 0.62

Cognitive stimulation

Parents taught child to count (age 4) 0.77

Parents taught child to write (age 4) 0.69

Parents taught child the alphabet (age 4) 0.67

Parents taught child his/her colours (age 4) 0.60

Eigenvalues 4.34 2.38 2.14 1.66

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Figure 7.2 Scree plot illustrating the 4-factor solution resulting from factor analysis of

parenting practices 0 1 2 3 4 E ig e n v a lu e s 0 5 10 15 20 Number of factors

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7.2.5.6 Parental interest

A measure of G1 parental interest in the school activities of G2 offspring at age eight was based upon responses from mothers on second generation survey questionnaires to items on teacher-parent contacts and teacher-parent communication. Parents with a maximum score of 4 had met and discussed their child’s progress with both the class teacher and head, while those with a score of 0 had done neither. This was a self-reported measure in contrast with the measure of parental interest in G0 parents, which was teacher-rated. Data on parental interest were available for 82% (1,386/1,690) of parent-offspring pairs.

7.2.5.7 Aspirations

A measure of G1 parental aspirations was based upon parental wishes, expressed when their child was aged eight years that the child should remain at school beyond the minimum school leaving age, together with their hopes for him or her progressing to some form of further education. This variable is a 5-point scale coded as (0) no aspirations (1) leave at age 15, the minimum school leaving age at the time; (2-3) leave at age 16 or 17; and (4) hopes for the G2 child staying on at school until age 18 or later. Data on parental aspirations were available for 82% (1,394/1,690) of parent-offspring pairs.

7.2.5.8 Corporal punishment

A binary measure of corporal punishment (yes/no) was derived from mothers’ responses to questions at ages four and eight asking them if they smacked their children as a form of punishment. Data on corporal punishment were available for 82% (1,393/1,690) of parent-offspring pairs.

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