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**NETWORK > EGO NETWORKS > BASIC MEASURES**

**PURPOSE **Compute standard ego network measures for every actor in a network.

**DESCRIPTION **This routine systematically constructs the ego network for every actor within the network and computes a collection of ego network measures. For directed data both in and out networks can be considered separately or together.

**PARAMETERS**

** Input network:**

Name of file which contains network to be analyzed. Data type: Digraph.

**Type of ego neighborhood:** (Default = UNDIRECTED)

Choices are:

**UNDIRECTED-**considers all actors connected to and from ego.

**IN-NEIGHBORHOOD**-considers only actors with a tie to ego.

**OUT-NEIGHBORHOOD**-considers only actors with a tie from ego.

**Output dataset **(Default = EgoNet)

Name of file containing ego-by-variable matrix.

**LOG FILE **A table of ego network measures. All measures exclude ties involving ego itself. The measures include the following:

**Size**. The number of actors (alters) that ego is directly connected to.

**Ties**. The total number of ties in the ego network (not counting ties involving ego).

**Pairs. **The total number of pairs of alters in the ego network -- i.e., potential ties.

**Density**. The number of ties divided by the number of pairs, times 100.

**AvgDist.** The average geodesic (graph-theoretic) distance between pairs of alters. If one or more pairs of alters cannot reach either other except through ego, this measure is undefined and will be blank.

**Diameter**. The longest geodesic distance within the ego network (unless infinite). If one or more pairs of alters cannot reach either other except through ego, this measure is undefined and will be blank.

nW**eakComp**. The number of weak components in the ego network.

pW**eakComp**. The number of weak components as a percentage of the number of alters.

**2StepReach. ** The number of nodes ego can reach within two steps divided by the number of nodes in the network excluding ego.

**ReachEffic.** The number of nodes ego can reach within 2 steps divided by the sum of the size of each of ego's alters. (It's an inverse measure of redundancy in the combined ego networks of ego and all of ego's alters. )

**Broker. **The number of times ego lies on the shortest path between two alters (i.e., the number of pairs of alters that are not directly connected).

**nBroker. **The previous measure normalized by number of brokerage opportunities, which is a function of ego network size.

**EgoBetweenness. **The sum of ego's proportion of times ego lies on the shortest path between each part of alters. For alters connected to each other, the contribution to between of that pair is 0, for alters connected to each other only through ego, the contribution is 1, for alters connected through ego and one or more other alters, the contribution is 1/k, where k is the number of nodes which connects that pair of alters.

** nEgoBetweenness. **Ego Betweenness normalized by a function of the number of nodes in the ego network.

**TIMING **O(N^3)** **

**COMMENTS **None

**REFERENCES **None