The band theory of solids provides a general framework with which to understand properties of materials. It not only explains the fundamental differences in electronic structure between insulators, semiconductors, and metals but also provides guidelines for finding optimum materials for specific device applications. For example, a semiconductor with a light effective mass is suited for high-electron-mobility transistors (HEMTs) because the mobility ${\mu }_{\mathrm{e}}$ is inversely proportional to the effective mass, ${\mu }_{\mathrm{e}}=e\tau /m^{*}$, where τ is the scattering time. For developing LEDs and laser diodes, a direct band gap material – i.e., a material in which the conduction-band bottom and the valence-band top occur at the same k – is necessary for momentum conservation since the momentum of photons is negligibly small compared with crystal momenta. In this chapter, after reviewing the basic concepts of atomic and molecular orbitals, bonds and bands, crystal lattices and reciprocal lattices, we provide an overview of the band structure of technologically important materials, including both traditional and emerging materials.

Derivational verbal bases, like those of nouns and adjectives, are built by combining the root morpheme (usually of three consonants) with a pattern of vowels and other modifications. The root + pattern base in verbs is organized into a group of verbal stems, which form a syntactic–semantic system. Various default settings of valence (§323), voice (§325), and Aktionsart (§328) are assigned to particular stems, although these settings can be neutralized or set aside in particular cases.

The linking of a main clause to a second, dependent clause which modifies the main clause adverbially is subordination. The linking is usually marked by a subordinating conjunction, although in some cases a coordinating conjunction is used, and the subordination is semantic rather than syntactic.

Nouns and noun phrases are used in clause roles such as subject, object, prepositional complement, nominal predicate, or (sometimes) adverbials.

This chapter introduces key terms used to describe experiments and, more generally, the investigation of cause and effect. Because so many different disciplines use experiments, layers of overlapping terminology have accumulated, and this chapter tries to cut through the clutter by grouping synonyms, thereby keeping jargon to a minimum. In addition to providing definitions, this chapter explains why these key concepts are important in practice. The chapter starts with the basic ingredients of an experiment (treatments, outcomes). Next, we define what we mean by a causal effect, introducing the concept of potential outcomes. The chapter culminates in the presentation of three core assumptions for unbiased causal inference. These core assumptions figure prominently throughout the book, as readers are continually encouraged to assess whether illustrative experiments satisfy these assumptions in practice.

Prior chapters relied on elementary statistical calculations and base R functions to analyze and visualize experimental results. This chapter builds on this foundation by showing how covariate adjustment using regression can be used to improve the precision with which treatment effects are estimated. Readers are shown how to apply regression to actual experimental data and to visualize multivariate regression results using R packages. This chapter also introduces the concepts of substantive and statistical “significance,” calling attention to the distinction between estimates of the average treatment effect that are large enough to be meaningful, even if they are not statistically distinguishable from zero. Examples of this distinction are provided using actual experimental data.

Independent personal pronouns are differentiated by person, gender, and number. They serve primarily as the subjects of copular and verbal clauses (§353). The 3mp/3fp pronouns also serve as direct objects in lieu of a dedicated 3mp object suffix.

Adverbs as such have no distinctive patterns or bases, and a breakdown of adverbial “shapes” would be unrewarding. Some adverbial expressions draw their form from other word classes such as adjectives and nouns, and only in such cases do they have a relation to triliteral derivation. Others are loanwords or prepositional phrases.

Social Science Experiments: A Hands-on Introduction is an accessible textbook for undergraduates. Why a hands-on approach that urges readers to roll up their sleeves and conduct their own experiments? When students design their own experiments, they must reflect on basic questions. What is the treatment … and control? Who are the participants? What is the outcome? The process of conducting an experiment builds other important skills: Creating a dataset, inspecting the results, and drawing inferences. Learning is easier when the motivation to acquire specific skills emerges organically through hands-on experience.

Adjectives, as noted (§81), are inflected in the same way as nouns, although there are some derivational patterns that are mainly used with adjectives (§§97, 110). They differ from nouns in having no intrinsic gender, agreeing with the gender of whatever noun they modify. This occurs when the adjective is used attributively (§145) or predicatively (§376).

Coordination is to be distinguished from the mere succession of clauses; it refers to clauses that are joined with some kind of cohesion between them, whether semantic (e.g., dealing with the same events or entities, or the same causal forces) or structural (with, e.g., pronominal reference, parallel syntax). As in subordinate clauses (ch. 18), one of the clauses comments on or proceeds in some way from the other, but syntactically both clauses are independent and could stand on their own. Typically, it is two clauses that are coordinated, but there are exceptions.