In the fall of 2011, Evans Data Corp conducted a worldwide survey of developers with the intent of documenting user satisfaction with the features of various SDKs used in mobile software development. Developers were asked to rank ten different features associated with the SDKs that they use. Each feature could be ranked as "excellent", "very good", "fair", or “needs improvement”. During processing, the four rankings were assigned a numerical value according to their relative significance. Values were then combined to produce an overall weighted score for each attribute. The relative values for each element ranked are displayed in graphs with the same scale, so that comparisons between graphs can be made. The numbers in the graphs only display relative values. In addition, developers assigned a ranking for the importance of each attribute, ranging from very important to not important at all. Then an overall score for all the SDKs was calculated using importance as a weighting factor.