Introduction to Quantitative Analysis: Confidence Intervals

Confidence intervals are range of values that make analysts fairly sure true values representing a distribution lie in. For instance, the confidence interval for a mean of a distribution indicates the range of values where there is a high degree of certainty that the true mean value lies (Padgett, 2016). The confidence interval for “Age” variable in the Afrobarometer survey data can be calculated using SPSS as shown below.

Table 1 Descriptives

Based on the SPSS output above, a 95% confidence interval for age gives an upper bound of 37.32 years and a lower bound of 37.07 years. The actual mean for the age of the participants is 37.19 years. The confidence interval indicates that, there is a 95% confidence that the true mean age lies between 37.07 and 37.32 years (Bryman, 2016) Typically, the confidence interval loosely quantifies the level of certainty that a particular population parameter lies.

Adjusting this value towards 100% increases the interval indicating that a high chance that the true population parameter such as the mean age lies in a particular wide range of values (Neuman, 2013). For example, if the confidence interval is adjusted to 99% the limits expands to between 37.03 and 37.36 years. For a social survey like the Afrobarometer, confidence intervals for a variable like age gives a more meaningful figures when reporting on the demographics of the participants. Such an aspect makes more sense when trying to understand other variables that are influenced by age such as access to medicare, income distribution, dependents in a particular region, and employment status – all these aspects are age-determined and the government can implement its social programs with an ideal knowledge of the population based on age distribution.

Table 2 Descriptive Statistics at 99% confidence level 

Table 2 Confidence Interval at 99% Confidence Level 

References

Neuman, W. L. (2013). Social research methods: Qualitative and quantitative approaches . Pearson education.

Bryman, A. (2016). Social research methods . Oxford university press.

Padgett, D. K. (2016). Qualitative methods in social work research (Vol. 36). Sage Publications.