A positive change in mentality can help Everton end their poor away run in the Premier League this season, manager Sam Allardyce said ahead of Saturday’s trip to Stoke City.The Merseyside club are on a five-match losing streak away from Goodison Park and have won just one of their 15 away league games this campaign, the same number as bottom-two sides Stoke and West Bromwich Albion.In contrast, ninth-placed Everton have won nine of their 15 home league matches to help them maintain their position in the top half of the standings.“We’ve tried a number of things. Changing system, changing personnel – but changing mentality is the big one,” Allardyce told reporters on Thursday.“We’ve been using some more work into the mind in the analysis room. Who we are, what we want to achieve, what we can get.“Visualising the performance you give at the top level and thinking of that to put yourself in a positive frame of mind… Tactically the preparation is fine but having a good frame of mind gives a better chance of it being delivered.”Allardyce identified Stoke playmaker Xherdan Shaqiri as their biggest threat, with the 63-year-old boss urging his team to mark the Swiss international carefully and stop him from influencing the game.Everton said on Wednesday that midfielder Gylfi Sigurdsson was expected to return from a knee injury in six to eight weeks but Allardyce is hopeful that the Iceland international can get back on the pitch ahead of schedule.“I’ve always felt it’s wrong to tag an injury with time limits,” Allardyce added. “You want to avoid setbacks. If you can get it before then you’ve done well.“We’ll look at it in the next two weeks. There’s a settling down period and then how quickly the player recovers. Gylfi is motivated to return for us and Iceland at the World Cup.”Stoke are 19th in the standings, a point adrift of the safety zone with eight games left to play.