1) Parental variables
Just as family's effect on children's game addiction is
significant [22], family's effect on children's smart phone
addiction is also substantial. Parental variables that affect
smart phone addiction are parents' education, age, income,
whether parents are working together, raising attitude,
attitudes towards smart phone, and addiction tendency.
In many studies, the lower the parents' income and
education [18] were, the higher the possibility of children
having problems [27] was. When parents' education is lower,
knowledge about seriousness of smart phone addiction is also
lower, so it is easy to give smart phone to their children,
resulting in higher smart phone addiction rate. Parents with
poor income cannot afford expensive smart phone, so their
children's smart phone addiction rate might be low. However,
adults' smart phone adoption rate has reached almost 90%,
and non-adoption group is limited to old-aged group, so
almost all low income parents have smart phones. They lack
resources to raise their children, so they easily let their
children use smart phones same as game addiction of children
[26]. Therefore, the lower the parents' income is, the higher
their children's smart phone addiction rate is.
Smart phone is a device which young people easily use and adopt pervasively. Younger parents tend to have more
generous adoption attitudes about smart phone, and higher
usage frequency. As a result, their children have higher
chance of contact and using smart phones, therefore having
higher smart phone addiction rate like internet addiction of
children [7].
Children from dual-income family have longer time alone
and because of lack of parent's amount of time to take care of
their children; they are generous about the requirements of
their children [11]. Therefore, they easily let their children use
smart phones, resulting in higher smart phone addiction rate.
Types of parenting can be divided into authoritarian,
permissive, and responsive [28]. Authoritarian is one-way and
rigorous way of raising children, strictly controlling their
children. Permissive is full of affection, inconsistent, and
laissez faire. On the other hand, responsive is respecting
children's autonomy, being consistent. Children from
authoritarian parents lack their own goals or judgments,
exclusive and aggressive. Children from permissive parents
are impulsive, selfish, stubborn, and hysteric. Children from
responsive parents have clear goals and decision of their own,
self-regulated and having high self-trust, they are likely to
have positive and harmonious interpersonal relationships.
Therefore, permissive parents are most likely to have children
with higher smart phone addiction rate [27].
In addition, parents' attitudes towards smart phone or usage
behaviors are likely to have influenced children's smart phone
addiction rate same as internet addiction of children [9].
When parents have more positive attitudes towards smart
phone, they let their children use smart phone more easily,
resulting in higher rate of smart phone addiction. Furthermore,
if parents themselves are heavy users of smart phone or
addicted to it, their children have higher chance to be exposed
to smart phones, resulting in higher smart phone addiction
rate.
2) Child variables
Child variables affecting child smart phone addiction are
child's age, gender, number of siblings, and whether they
attend education institutions or not.
The lower child's age is, mental development is incomplete
and easily immersed, having higher possibility of smart phone
addiction [10]. In addition, boys tend to have more curiosity
about tools and needs for trial. Also, boys tend to be more
distractive and lack of self-control [14], so they have higher
possibility of addiction to smart phone. While higher number
of siblings means higher possibility of interacting with other
people, lower number of siblings means more time spending
alone, resulting in higher possibility of addiction to digital
tools like smart phones [15]. In addition, when a child attends
education institutions like preschool or kindergarten, they are
likely to be under teacher's control and have more time to
interact with peers, resulting in lower smart phone addiction
rate. On the other hand, children not attending any education
institutions have more time alone at home and because of lack
of parents' resources, they have higher possibility of smart
phone addiction.