MongoDBをインストール後、エラーにより接続できません

初心者です。

mac OS X El capitanを使用しています。

先程、mongoDBをインストールし、利用しようとここみたところ

MongoDB shell version: 3.2.1
connecting to: test
2016-01-27T13:38:00.259+0900 W NETWORK [thread1] Failed to connect to 127.0.0.1:27017, reason: errno:61 Connection refused
2016-01-27T13:38:00.259+0900 E QUERY [thread1] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed :
connect@src/mongo/shell/mongo.js:224:14
@(connect):1:6

exception: connect failed

と表示され、困っております。

同様のご質問が先にありましたので、参考にさせていただきましたが自分では解決できませんでした

vim /usr/local/var/log/mongodb/mongo.logでログを確認したところ、

2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] MongoDB starting : pid=11269 port=27017 dbpath=/usr/local/var/mongodb 64-bit host=xxxxxxxxxxpro.local
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] db version v3.2.1
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] git version: a14d55980c2cdc565d4704a7e3ad37e4e535c1b2
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] allocator: system
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] modules: none
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] build environment:
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] distarch: x86_64
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] target_arch: x86_64
2016-01-27T13:07:49.632+0900 I CONTROL [initandlisten] options: { config: "/usr/local/etc/mongod.conf", net: { bindIp: "127.0.0.1" }, storage: { dbPath: "/usr/local/var/mongodb" }, systemLog: { destination: "file", logAppend: true, path: "/usr/local/var/log/mongodb/mongo.log" } }
2016-01-27T13:07:49.633+0900 E NETWORK [initandlisten] Failed to unlink socket file /tmp/mongodb-27017.sock errno:13 Permission denied
2016-01-27T13:07:49.633+0900 I - [initandlisten] Fatal Assertion 28578
2016-01-27T13:07:49.633+0900 I - [initandlisten]

***aborting after fassert() failure

と表示されました。

Failed to unlink socket file /tmp/mongodb-27017.sock errno:13 Permission denied
のところが問題かと思われますが、何卒お力をお借りできれば幸いです。
よろしくお願い致します。

追記します
mongodを入力したところ
xxxxxxxxxxxxpro:~ xxxx$ mongod
2016-01-27T14:20:06.155+0900 I CONTROL [initandlisten] MongoDB starting : pid=11424 port=27017 dbpath=/data/db 64-bit host=sharaquemacbookpro.local
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] db version v3.2.1
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] git version: a14d55980c2cdc565d4704a7e3ad37e4e535c1b2
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] allocator: system
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] modules: none
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] build environment:
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] distarch: x86_64
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] target_arch: x86_64
2016-01-27T14:20:06.156+0900 I CONTROL [initandlisten] options: {}
2016-01-27T14:20:06.196+0900 I STORAGE [initandlisten] exception in initAndListen: 98 Unable to create/open lock file: /data/db/mongod.lock errno:13 Permission denied Is a mongod instance already running?, terminating
2016-01-27T14:20:06.196+0900 I CONTROL [initandlisten] dbexit: rc: 100