of the survey. However, in specifications that compare the 2014 survey to the 2005 survey, households surveyed during July (Ramadan in 2014) or October (Ramadan in 2005) in either survey were excluded. However, it is important to note that the estimates are qualitatively identical when all interviewed households are included.

# **4. Empirical Strategy**

Based on this setting, this article utilizes a difference-in-difference strategy to analyze the effects that the capture of Sana’a had on household expenditure and coping strategies. Figure 3 illustrates the strategy by plotting average annual household expenditure and a number of key coping strategies by month of the survey. Expenditure in Sana’a was maintained in October of 2014 on average, but by November and December, there was a sharp decline in expenditure such that there was little difference in expenditure between the city of Sana’a and the rest of Yemen despite the poverty rate being approximately four times less in the city of Sana’a (Appendix 1). Importantly, over the same time period, there was little change in expenditure in the rest of Yemen, and this pattern is similar for a number of other coping strategies that are observable in the survey.

Formalizing this empirical strategy, this article estimates the following specification: where i refers to household, r refers to region, _Post_ _~~M~~ onth_ _~~j~~_ are indicators equaling one if the household was interviewed during the j’th month following the occupation<sup>16</sup> , _Capital_ denotes an indicator equal to one if the household is from the city of Sana‘a, _Y_ includes all lower-order terms (each of _Post_ _~~M~~ onthj_ and _Capital_ ), and _X_ is a vector of individual control variables.<sup>17</sup> The baseline estimates restrict the households in specification (1) to households surveyed in the three non-Ramadan months prior to the capture and the three months following the capture of the city that the survey continued. Standard errors are clustered at the PSU level, and observations are weighted to make the estimates representative of the population. The coefficients of interest are _βj_ , which represent how much larger the percentage point change was in Sana’a (relative to the three months before the capture) than in the rest of Yemen for a variety of outcomes following the capture of the city.<sup>18</sup>

> 16Specifically, _Post Month_ ~~1~~ , _Post_ _~~M~~ onth_ ~~2~~ , and _Post_ _~~M~~ onth_ ~~3~~ respectively are indicators equaling one if the household was surveyed in October, November, and December.

> 17Control variables include household size, an indicator for whether the household head is married, the household head ever attended school, an indicator if the household head was a smoker, an indicator if the household head chews Qat, the years of schooling of the household head, an indicator whether the household has a child, an indicator if the household’s dwelling is made of cut stone, an indicator equaling one if the walls if the household’s dwelling were made of other material, an indicator equaling one if the household’s roof that was made of reinforced concrete, an indicator equaling one if the household’s roof was made of wood and concrete, an indicator equaling one if the household’s roof was made of mud, an indicator if the household’s floor was made of concrete, an indicator equaling one if the household’s floor was made of tile, an indicator equaling one if the household had a flush toilet, and an indicator if the household was rural.

> 18Although the baseline specification is restricted to balance the number of pre and post-months and to use the pre-months that are closest in time to the capture of the city, Appendix 4 demonstrates that the results

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