interest similarity, I include a dummy variable coded 1 if one of the states in the dyad was

a colony of the other state at some time in its history (

COLONIAL

RELATIONSHIP

) .

*Model Specification*

The base model (Model 1), which is laid out in equation (1) below, is a fixed

effects model with robust standard errors clustered on the dyad. Table 1 presents

descriptive statistics for the variables in the model. It is important to note also that the

LOWMEMBERS

IGO

MEMBERSHIP

variable is lagged by five years for both theoretical and

methodological reasons. Since I seek to explain state interest convergence, it makes

sense that I look at the effect that membership in IGOs with certain institutional attributes

has on interest similarity five years later. As noted above, socialization theory proposes

that socialization occurs as the result of repeated meetings over long periods of time .

Therefore, I expect socialization effects to take several years to be reflected in state

interests. Indeed, when looking at the effects of structured IGOs on interest convergence,

the IGO effect increased with each additional time lag up to four years (See Figure 1) .

**Equation 1:**

**AFFINITY**

**XT**

** = B**

**0**

******Constant* + B

**1**

*****

**AFFINITY**

**XT**

**-1 **

**+ B**

**2**

*****

**LOWMEMBERS**

** **

**IGO**

** **

**MEMBERSHIP**

**XT**

**-5**

** + **

**B**

**3**

*****

**EXTRA**

**-**

**IGO**

** **

**CONTACT**

**XT**

** + B**

**4**

*****

**DOMESTIC**

** **

**POLITICAL**

** **

**DIFFERENCE**

**XT**

** + B**

**5**

*****

**DYADIC**

** **

**TRADE**

**XT**

** + **

**B**

**6**

*****

**RELATIVE**

** **

**ECONOMIC**

** **

**DEVELOPMENT**

**XT**

** + B**

**7**

*****

**RELATIVE**

** **

**ECONOMIC**

** **

**SIZE**

**XT**

** + B**

**8**

*****

**RELATIVE**

** **

**MILITARY**

** **

**POWER**

**XT**

** + B**

**9**

*****

**JOINT**

** **

**MILITARY**

** **

**ALLIANCE**

**XT**

** + B**

**10**

*****

**COLD**

** **

**WAR**

**XT**

** + B**

**11**

*****

**GEOGRAPHIC**

** **

**DISTANCE**

**X**

** + B**

**12**

*****

**COLONIAL**

** **

**RELATIONSHIP**

**X**

** **

26