State in clear and simple terms how you came up with all estimates.

The estimates were derived using the following assumptions and models. Firstly, a linear regression model was used to determine the relationship between physical activity level and depression symptom severity. Utilising this data, it was then possible to estimate how much of an improvement could be achieved through engaging in regular exercise. Secondly, a multi-variate logistic regression model was employed to assess the effect of physical activity on quality of life outcomes among elderly people with arthritis over six months. This allowed for estimation of expected improvements in the health related quality of life scores due to increased levels of physical activity.

Additionally, a survey study conducted by Ahmed et al (2017) provided evidence which suggested that approximately 70% of individuals who participated in regular exercise programs experienced alleviated symptoms from their depression within 6 months when compared to those who did not engage in any form of exercise at all. Based on this information it can be estimated that depressive symptom severity should improve significantly over time if such interventions are adopted on a regular basis.

It is also important to note that these results will vary greatly depending upon individual circumstances as well as other factors such as lifestyle choices or pre-existing medical conditions which may have an impact upon the outcome. Therefore, any estimates made should be taken with caution and further research needs to be done in order gain more accurate insights into potential improvements associated with particular interventions before implementing them into practice across different populations and settings.