The Mark account of these miracles begins with Jairus as having approached Jesus on behalf of his ailing daughter who will die without the divine intervention of Jesus. After Jesus agrees to go and see Jairus' daughter, he is "interrupted" by the woman with the issue of blood. Jesus takes the time to heal this woman, and it is then revealed by those in the ruler's household that Jesus' services are no longer needed, as his daughter has died in the meantime. Jesus continues his journey anyway, and raises Jairus' daughter from death. It's a remarkable account of his power, authority, and compassion.
The perplexing bit comes in that Matthew's parallel account of these same miracles, the chronology of events is just a little bit different (the chronology of Luke's parallel account agrees with Mark's). You can read Mark's account here, Matthew's here, and Luke's here.
The discrepancy between Matthew and Mark (and also Luke) is the order of the interactions between Jairus and Jesus, and the woman and Jesus. In Mark's account, Jairus makes an initial contact with Jesus, in which it appears his daughter is still alive and he needs Jesus' help in order to keep her that way. After this initial interaction, the woman with the issue of blood is healed. Then Jesus and Jairus receive word that in the meantime the girl has passed away. Jesus continues to her house anyway, and raises her from the dead. Matthew's account, however, has a different order of events: he reports that the first interaction between Jesus and Jairus is when it is revealed that his daughter is dead, and then the woman with the issue of blood is healed, and then Jesus continues on to do what he had started to do: raise a girl from death. If we put the events of these narratives into a flow chart it would look like this, moving from left to right (click to enlarge):
As you can see, there's a discrepancy between the order of events and communication between Matthew and Mark (and Luke, which has the identical order as Mark). Does Jesus learn that Jairus' daughter has died before or after he heals the woman with the issue of blood? This morning I shared the conundrum with my fellow pastors and we each set to checking our commentaries to find a scholarly explanation, but to no avail. In fact, between the three of us, we checked more than a half dozen commentaries but this discrepancy was not noted in any of them (other than one commentary whose author asserted the possibility that the healing of the woman with the issue of blood and the raising of Jairus' daughter were two unique situations and were only crammed together in the gospel accounts at a later date, but this interpretation is unlikely at best, for a variety of reasons that I won't go into here). So without any scholarly support, we came up with two possible reasons why there is a difference in chronology between Matthew's and Mark's accounts of these miracles.
1. It is possible and even likely that Matthew wasn't concerned with chronology in his recounting of these miracles. He simply wanted to get the story out there in as few words as possible. The exact order in which Who said What wasn't important to him. What was important was that he told the story of these two miracles, and relayed how they proved his Lordship and status as the Messiah (which is the ultimate goal of Matthew's gospel). He wanted to communicate the facts: A girl died; Jesus went to raise her from death; in the process, he healed a woman with an issue of blood; then he raised the girl from death. That's it.
2. A second possibility is that the language used by Mark and Luke refer to the state of death in meaning but are translated literally as indicating that she was still suffering from the illness that presumably caused her death. For example, in Mark 5.23 Jairus says, "My little daughter is at the point of death. Come and lay your hands on her, so that she may be made well and live." What is Jairus saying in this statement? Is he saying that his daughter is very sick? Is he saying that she only has 6 months? Is he saying that her condition is "moment to moment," meaning that she could die at any second? Is he saying that she's "as good as dead"? Or, is it possible that he is communicating that she is already dead? Also note that Jairus says that he needs Jesus to do something in order for his daughter to "live." Could it be that in Mark 5.23 Jairus is declaring to Jesus that his daughter is dead? If so, then it accords well with Matthew 9.18. (Note: a similar interpretation can be made of Jairus' statement as it is recorded in Luke if one examines the grammar of the Greek.) The problem with this interpretation is that if Jairus is declaring her as being dead in Mark 5.23, then why do people from his household come to tell him in Mark 5.35 that she has died and not to trouble the Teacher any further?
Of these two possibilities, I'll appeal to Occam's Razor in leading me to go with the former as an explanation for the discrepancy between Matthew's and Mark's accounts of these miracles. That is, I believe that Matthew was simply concerned with communicating the facts of the story, rather than recreating a precise chronology. It should be further noted that this discrepancy does not at all call the reliability of the Bible into question, as I have raised two worthy explanations as to why the difference exists. When we think about context and the author's purpose in writing, most difficulties in the text can be reasonably explained.