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When comparing nebular electron densities derived from collisionally excitedlines (CELs) to those estimated using the emission measure, significantdiscrepancies are common. The standard solution is to view nebulae asaggregates of dense regions of constant density in an otherwise empty void.This porosity is parametrized by a filling factor $f<1$. Similarly, abundanceand temperature discrepancies between optical recombination lines (ORLs) andCELs are often explained by invoking a dual delta distribution of a dense,cool, metal-rich component immersed in a diffuse, warm, metal-poor plasma. Inthis paper, we examine the possibility that the observational diagnostics thatlead to such discrepancies can be produced by a realistic distribution ofdensity and temperature fluctuations, such as might arise in plasma turbulence.We produce simulated nebulae with density and temperature fluctuationsdescribed by various probability distribution functions (pdfs). Standardastronomical diagnostics are applied to these simulated observations to deriveestimates of nebular densities, temperatures, and abundances. Our results showthat for plausible density pdfs the simulated observations lead to fillingfactors in the observed range. None of our simulations satisfactorily reproducethe abundance discrepancy factors (ADFs) in planetary nebulae, although thereis possible consistency with \ion{H}{ii} regions. Compared to the case ofdensity-only and temperature-only fluctuations, a positive correlation betweendensity and temperature reduces the filling factor and ADF (from optical CELs),whereas a negative correlation increases both, eventually causing the fillingfactor to exceed unity. This result suggests that real observations can provideconstraints on the thermodynamics of small scale fluctuations.

Realistic Models for Filling and Abundance Discrepancy Factors in Photoionised Nebulae