ERG theory was intended to be an improvement over Maslow's theory, but it has only fared a little better with regard to research support. Alderfer's (1969) original work found support for the theory, but later tests only found mixed support. For example, when Wanous and Zwany (1977) examined whether people reported levels of work need-fulfillment related to existence, relatedness, and growth, they found good support for the growth category, moderate support for the existence category, and weak support for the relatedness category. They also only found partial support for the idea that need satisfaction at one level would affect need importance at another level.
ERG theory can be applied to organizations in a similar fashion to Maslow's Hierarchy in that managers can assess the need level of their employees and then seek to meet those needs in the workplace. If an employee's growth needs are frustrated and there is little opportunity to make the job more challenging or enriching (e.g., assembly-line work), the manager might try to ensure that the employees' relatedness and existence needs are met through work.
ERG theory has helped to lay the groundwork for future theories that involve need satisfaction as a key component. The major strength of ERG theory is that it is more flexible and less restrictive than the need hierarchy. In addition, research has been more supportive of Alderfer than of Maslow, but the level of empirical evidence is far from strong.
ERG suffers from many of the same shortcomings of Maslow's theory in terms of the lack of consistent research support and a precise definition of growth needs, as well as the difficulty of measuring needs. In addition, needs are nebulous for trying to counsel employees on how they can improve motivation or performance.