# **4.5. Comparison between Ghana and Tanzania**

As mentioned earlier, this study follows the design of a survey experiment conducted in the Mara region of Tanzania in 2014 (Arthi et al 2018). The main difference in design of the two experiments is related to the way information was captured for the recall group. In the Tanzania case, the recall households were interviewed only once at the end of the season. In Ghana, the recall households were visited at the beginning of the agricultural season for the baseline survey, which collected an initial listing of plots and household workers, and again at the end of the season. The Tanzania approach allows for the comparison of the treatment group with what would be a ‘typical’ cross-sectional household survey that is conducted at the end of the agricultural season without any information from the start or during the season. Conversely, the Ghana approach resembles a panel survey and enables us to control for differences in baseline characteristics and disentangle the possible sources of recall bias by allowing more rigorous estimates of listing bias.

**Table 11** summarizes the results of both studies. Columns 3 and 4 replicate **Table 2** , and columns 1 and 2 are the equivalent numbers for Tanzania. Weekly visit households in Tanzania report 39.5 hours of farm labor per person per plot, which is significantly less than in Ghana (106.4 hours). However, this difference can be easily explained by differences in plot size, with plots being much smaller in Tanzania (0.33 ha) than in Ghana (1.19). What is much more striking is the large difference in (unconditional) recall bias – 18 percent in Ghana, versus 207 percent in Tanzania. What would explain such large differences in the magnitude of recall bias?

**Table 11: Farm labor per person per plot, Ghana and Tanzania**

||**Tanzania**<br>**Weekly**<br>**Visit**|<br>**Recall**|**Ghana**<br>**Weekly**<br>**Visit**|**Recall**|
|---|---|---|---|---|
|Hours|39.5|121.3***|106.4|125.7***|
||(69.5)|(133.8)|(2.81)|(4.75)|
|Plot Size (ha)|0.33|0.31<br>|1.19|1.32***|
||(0.007)|(0.01)<br>|(0.02)|0.03)|

Note: *** Denotes significantly different from weekly visit estimate at 1%. Standard errors are reported in parenthesis below the coefficient estimates.

**Table 12** provides information on listing bias in Ghana and Tanzania, that helps to understand the difference in recall bias shown in the previous table. The simple difference estimator of listing bias presented in the top panel is equal to the difference in the average number of workers (plots) at endline between weekly visit and recall households and can be compared between Ghana and Tanzania. The bottom panel shows the double difference estimator of listing bias, which nets out baseline differences. Given that Tanzania did not collect baseline information for recall households, the double difference estimator can only be calculated for Ghana.

**Table 12: Listing bias, Ghana and Tanzania**

|||**Tanzania**|**Ghana**|
|---|---|---|---|
|Listing Bias|Workers|-1.6***|-1.5***|
|(Simple Difference)|Plots|-2.1***|-0.6***|
|Listing Bias|Workers|N/A|-1.2***|
|(Double Difference)|Plots|N/A|-0.3***|

Note: *** Denotes significantly different from weekly visit estimate at 1%.

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