Demand analysis for selected roots and tubers among urban households of Nakuru County, Kenya

Figures & data

Table 1. Description of variables and descriptive statistics

Variables	Description of variables and their measurements	Range	Mean
Continuous variables
Age	Average age of the decision-maker^2 in years	18.00–72.00	40.00
Education	Average years of education of the decision-maker	1.00–27.00	13.00
H_size	Average household size	1.00–12.00	4.00
Prop_house1	Proportion of household members 18 years and below	0.00–0.75	0.31
Prop_house2	Proportion of the household members 19 years and above	0.25–1.00	0.69
Prop_incfood	Proportion of monthly income allocated to food items	0.02–0.90	0.34
lnExp	Natural log of R&Ts real^3 monthly expenditure in KES^4	3.25–7.99	5.69
In (p1, … p5)	Natural log price per kilogram of Irish potatoes, Sweet potatoes, Cassava, Arrowroots, and Yams, respectively
IMR	Inverse Mills Ratios
Categorical variableCount Percentage
Gender	Average % of male decision-makers	184	48.00

Table 2. Household expenditure on R&Ts

R&T category	Mean budget shares	Mean expenditure (KES)	Participation rate
Irish potato	0.4211	628.26	77.40
Sweet potato	0.2514	380.52	60.52
Cassava	0.0683	128.70	22.34
Arrowroot	0.1867	394.55	41.56
Yam	0.0725	139.09	22.34

KES refers to Kenyan shilling (official Kenyan currency); exchange rate is 1 $US = KES. 113.05

Table 3. Maximum likelihood estimates of the household socio-economic and demographic effects using LA/AIDS

Share	Age	Gender	Education	H_size	Prop_house1	Prop_house2	Prop_incfood	IMR
Irish potato	−0.070(0.057)	0.033(0.027)	0.058(0.045)	0.007(0.036)	0.642(0.646)	0.857(0.841)	0.010(0.033)	0.275***(0.028)
Sweet potato	0.111**(0.048)	0.032(0.023)	0.064**(0.032)	−0.038(0.032)	0.752(0.562)	0.865(0.732)	0.017(0.028)	0.423***0.043
Cassava	−0.066***(0.020)	−0.005(0.009)	−0.054***(0.013)	−0.039***(0.013)	1.006***(0.233)	1.230***(0.303)	0.009(0.011)	−0.285***(0.011)
Arrowroot	0.049(0.052)	−0.000(0.024)	0.034(0.034)	−0.038(0.034)	0.019(0.603)	−0.058(0.785)	0.003(0.030)	−0.170***(0.028)
Yam	0.022(0.017)	0.009(0.008)	0.019*(0.011)	0.004(0.011)	−0.777***(0.199)	−1.080***(0.260)	0.002(0.010)	−0.316***(0.010)

***, **, * = Significant at 1%, 5%, and 10%, respectively.

Table 4. Maximum likelihood estimates of the R&Ts categories price and expenditure effects using LA/AIDS

	${\alpha }_i$			Prices			${\beta }_{ij}$
R&Ts Shares		Price_irish potato	Price_sweet potato	Price_cassava Price_arrowroot		Price_yam	Expenditure
	(Intercept)	(P1)	(P2)	(P3) (P4)		(P5)	Coef.
Irish potato	0.311(0.624)	0.056(0.085)	0.021(0.046)	−0.028(0.036)	−0.041(0.068)	−0.008(0.032)	−0.127***(0.020)
Sweet potato	−0.589(0.533)	0.021(0.046)	0.065(0.047)	0.001(0.019)	−0.083**(0.042)	−0.004(0.017)	−0.108***(0.017)
Cassava	0.404*(0.214)	−0.028(0.036)	0.001(0.019)	0.023(0.042)	−0.003(0.036)	0.008(0.031)	−0.075***(0.007)
Arrowroot	−0.216(0.569)	−0.041(0.068)	−0.083**(0.042)	−0.003(0.036)	0.098(0.083)	0.028(0.033)	0.053***(0.017)
Yam	1.517***(0.194)	−0.008(0.032)	−0.004(0.017)	0.008(0.031)	0.028(0.033)	−0.025(0.041)	−0.077***(0.006)

***, **, * = Significant at 1%, 5%, and 10%, respectively.

Table 5. Price and expenditure elasticities

Expenditure share category	Irish potato	Sweet potato	Cassava	Arrowroot	Yam
Marshallian/uncompensated elasticities
Irish potato	−0.739	0.125	−0.046	−0.041	0.003
Sweet potato	0.263	−0.635	0.033	−0.248	0.017
Cassava	0.048	0.288	−0.594	0.157	0.196
Arrowroot	−0.338	−0.514	−0.037	−0.526	0.131
Yam	0.337	0.216	0.182	0.588	−1.268
Hicksian/compensated elasticities
Irish potato	−0.446	0.301	0.001	0.090	0.054
Sweet potato	0.503	−0.492	0.072	−0.142	0.058
Cassava	0.008	0.264	−0.601	0.139	0.189
Arrowroot	0.202	−0.191	0.051	−0.287	0.224
Yam	0.314	0.202	0.179	0.578	−1.272
Expenditure elasticities
	0.698	0.570	−0.095	1.284	−0.056

*In bold diagonally are the Marshallian and Hicksian own-price elasticities*.