On various definitions of shadowing with average error in tracing

In this paper we present a systematic study of shadowing properties with average error in tracing such as (asymptotic) average shadowing, $\underset{‾}{d}$-shadowing, $\bar{d}$-shadowing and almost specification. As the main tools we provide a few equivalent characterizations of the average shadowing property, which also partly apply to other notions of shadowing. We prove that almost specification on the whole space induces this property on the measure center. Next, we show that always (e.g. without assumption that the map is onto) almost specification implies asymptotic average shadowing, which in turn implies the average shadowing property and consequently also $\underset{‾}{d}$-shadowing and $\bar{d}$-shadowing. Finally, we study connections among sensitivity, transitivity, equicontinuity and (average) shadowing.