Adherent cultures of E10.5 rat neuroepithelial cells (NEP cells) from the caudal neural tube require FGF (fibroblast growth factor) and CEE (chick embryo extract) to proliferate and maintain an undifferentiated phenotype in culture. Epidermal growth factor (EGF) does not support E10.5 NEP cells in adherent culture and NEP cells do not form EGF-dependent neurospheres. NEP cells, however, can be grown as FGF-dependent neurospheres. NEP cells express nestin and lack all lineage-specific markers for neuronal and glial sublineages, retain their pleuripotent character over multiple passages, and can differentiate into neurons, astrocytes, and oligodendrocytes when plated on laminin in the absence of CEE. In clonal culture, NEP cells undergo self-renewal and generate colonies that vary in size from single cells to several thousand cells. With the exception of a few single-cell clones, all other NEP-derived clones contain more than one identified phenotype, with over 40% of the colonies containing A2B5, beta-111 tubulin, and GFAP-immunoreactive cells. Thus, NEP cells are multipotent and capable of generating multiple neural derivatives. NEP cells also differentiate into motoneurons immunoreactive for choline acetyl transferase (ChAT) and the low-affinity neurotrophin receptor (p75) in both mass and clonal culture. Double labeling of clones for ChAT and glial, neuronal, or oligodendrocytic lineage markers shows that motoneurons always arose in mixed cultures with other differentiated cells. Thus, NEP cells represent a common progenitor for motoneurons and other spinal cord cells. The relationship of NEP cells with other neural stem cells is discussed.

Threats to the validity of inferences and conclusions regarding the effects of applied interventions have been a major dilemma for social scientists and evaluators for several decades. One mechanism for reducing threats to internal validity and improving warrants for cause-and-effect conclusions in nonrandomized investigations and evaluations is the inclusion of nonequivalent dependent variables as an element of structural design.In this chapter, the rationale for, history of, and examples from practice for using nonequivalent dependent variables to reduce internal validity threats, as well as some warrants supporting their increased use, are described.

Although investigations into evaluation theories, methods, and practices have been occurring since the late 1970s, research on evaluation (RoE) has seemingly increased in the past decade. In this review, 257 studies published in 14 evaluation-focused journals over a 10-year period (between 2005 and 2014) were identified as RoE and then classified according to Henry and Mark's and Mark's taxonomies of RoE. The majority of RoE published in evaluation-focused journals consists of descriptive studies and, to a lesser extent, comparative studies of evaluation practices. Few investigations, however, address questions pertaining to values or valuing in evaluation, ethics, or evaluation consequences. Gaps in and an agenda for future RoE are discussed.

Research on evaluation theories, methods, and practices has increased considerably in the past decade. Even so, little is known about whether published findings from research on evaluation are read by evaluators and whether such findings influence evaluators' thinking about evaluation or their evaluation practice. To address these questions, and others, a random sample of American Evaluation Association (AEA) members and a purposive sample of prominent evaluation theorists and scholars were surveyed. A majority of AEA members (80.95% + 7.60%) and sampled theorists and scholars (84.21%) regularly read research on evaluation and indicate that research on evaluation has influenced their thinking about evaluation and their evaluation practice (97.00% + 3.38% and 94.00% + 4.79%, for AEA members, and 100% and 100%, for prominent theorists and scholars, respectively).

Internet surveys of American Evaluation Association (AEA) members are a common method for studying evaluation practice. Response rates obtained from Internet surveys of AEA members are, however, frequently very small. To investigate whether or not material incentives increase response rates to Internet surveys of AEA members, a between-subjects three-treatment and one control randomized experiment in which a randomly selected sample of AEA members were randomly assigned to a no-incentive control condition, lottery condition, token incentive condition, or philanthropic donation incentive condition was utilized. The overall response rate to the survey was 39.66% and the response rates for each of the four conditions were control = 36.24%, lottery = 44.39%, token incentive = 43.28%, and philanthropic donation = 34.67%, respectively. The cost-effectiveness of each of the four conditions also was examined, demonstrating that the lottery was the most cost-effective. Other factors potentially influencing response or nonresponse decisions also are discussed.