In literature, there are many definitions of Independent and dependent variables, which help in predicting a reason for an event to happen. Sometimes, they are misleading, as according to the context, independent variable can become dependent and vice versa. For nursing practice, according to Polit & Beck (2006), the created variables, like drug delivery through different routes, or behavioral pattern that might cause a life style change, are considered the independent variables. Consequently, the associated effects like suppression of disease related abnormalities, physiological changes etc., are the dependent variables.
To cite an example, to what extent lung cancer (dependent variable) is caused by smoking (independent variable). If onset of cancer initiates secondary manifestations, then the former becomes independent, whereas the consequences thereof, get dependent variables’ status. Another example is the effect of tactile stimulation (independent variable) on weight gain of premature child (dependent variable). Multiple independent variables may have single dependent variable and reverse is also possible. For more than one variable, the data are statistically treated to calculate the correlation co-efficient, which provides information on the causal (predicator) variable most affecting the dependent variable at a given degree of freedom (Bulmer, 1979).
A paper authored by Molt et al. (2008) has given an account on the relationship between symptoms associated with multiple sclerosis and loss of physical activity in the patients. In an earlier paper (Molt et al., 2005), the authors described that multiple sclerosis is a congenial, widespread central nervous system disease, whose symptoms is highly variable, and may include fatigue, tremors, loss of balance and co-ordination, mild paralysis, pain and depression. There are also social factors, like rejection, isolation, that might eventually lead to loss of physical activity. The patients consequently gain weight, become hypertensive and suffer from type-II diabetes.
Since multiple sclerosis is clinically non-curable disease, the focus has been more on its management and rehabilitation. In both the studies, the general and disease-specific symptoms as independent variables were recorded and quantified by collecting data sheet from approved sample size of the patients. These factors were correlated with a dependent variable, that is, loss of physical activity, which was recorded using approved objective devices – accelerometer and pedometer.
For controls, the same independent and dependent parameters were compared for non-diseased persons and the patients suffering from other diseases like cerebral palsy. In the correlation analysis, it seems that difficulty in walking (independent variable) was correlated with loss of physical activity (dependent variable) to the highest extent. The authors must have found significant difference (at say, P = 0.001) between the attributes tested for groups: multiple sclerosis patients and healthy/patients with other diseases to conclude the predicate variable (difficulty in walking) as one of the major causes for lose of physical activity.
Apart from neuro-muscular treatments, these analyses help considerably to devise effective exercise schedules for recovery from the physical inactivity. The fitness programs are discussed by Boutin et al. (2004). Accordingly, to improvise the walking and mild jogging efficiency in the patients, mild aerobic or resistance exercise training in physiotherapy, would enhance lactate tolerance and enhance VO2max. As it is correlated with improvisation of physical activity, the process will enhance the general life style. In conclusion, many independent variables should be considered to relate with a dependent variable, attributed to physical/mental disability. Such methods help to deduce the most causative variable for effective treatment/rehabilitation practices.
References:
Boutin, P., Plante, M. and Rivard, D. (2004). MS and Fitness – Guide for people with multiple sclerosis. Quebec: Multiple Sclerosis Society of Canada.
Bulmer, M.G. (1979). Principles of Statistics (2nd Ed.). New York: Dover Publications Inc.
Motl, R.W., McAuley, E. and Snook, E.M. (2005). Physical activity and multiple sclerosis. Multiple Sclerosis, 11, 459-463.
Motl, R.W., Snook, E.M. and Schapiro, R.T. (2008). Symptoms and physical activity behavior in individuals with multiple sclerosis. Research in Nursing & Health, 31(5), 466-475.
Polit, D.F. and Beck, C.T. (2006). Essentials of Nursing Research – Methods, Appraisal and Utilization. Philadelphia: Lippincott Williams & Wilkins.