Sample of Statistical Design

The research study used multiple linear regression stepwise analysis of the effect of temperature to moisture removal from the raw material feed and dryness quality of the three fruits used as experimental tool with respect to the design of the modular dehydrator.

Multiple regression analysis is a multivariate statistical technique that simultaneously probe into the underlying relationships among the given set of variables. The relative magnitude of the dependent relationships is estimated simultaneously enabling the researcher to identify a set of possible predictors of the criterion variable. The formula for multiple regression is ? = a  + b1X1 + b2X2 + b3X3 + ………… + bn-1Xn-1
Where: ? = the variable to be predicted
a  = constant or intercept
b1- bn-1 = slopes of the predictor variables
X1 – Xn-1 = are the values of predictor variables

The slopes of the predictor variables can be calculated by means of the standardized beta weights, ? with respect to the standard deviations of the variables involved in the study being conducted. Multiple regression analysis includes a multiple coefficient of determination symbolized by R2, the proportion of variance in a dependent variable explained by a set of independent variables in combination.
R2 = rxy2 + rzy2 – 2*rxyrzyrxz
1 – rxz2

From the multiple linear regression equation, the slopes of the predictor variables indicate the change in the dependent variable associated with a unit increase in a given predictor, holding constant the other predictor.

To calculate the percentage moisture removed per hour of drying temperature,
MR = mi – mo
where: MR = percentage moisture removed per hour
mi = initial mass load
mo = mass per hour

To be able to know the approximate water content of the fruit to undergo dehydration and the weight reference thereafter:

Mwc = mi * %wc (1)       mwr = mw * %wcstd (2)          mdry = mi – mwr

Where: mwc = water content of food, gram water/gram fresh material
mi = initial mass feed
mwr = amount of water to be removed
wcstd = standard water content in percentage of food
mdry  = mass of dried food, gram dry basis/gram fresh material