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.

The theory of the interaction of radiation with matter is fundamentally important for describing how modern semiconductor devices generate, detect, and modulate light. These devices, known as optoelectronic devices, are behind today’s technology in diverse areas, including communications, imaging, spectroscopy, sensing, and energy harvesting. They may also become essential components in future quantum technology based on photons. In this chapter we will learn the basic theoretical formalism for describing light–matter interaction phenomena, starting from microscopic processes such as absorption, spontaneous emission, and stimulated emission and ending with the conditions for achieving gain, which is a fundamental requirement for a laser.

Numerals and other words signify the quantity of an entity. The cardinal numbers are not adjectival in that they do not identify or describe a noun but rather indicate how many or how much of something there is. The ordinals, however, are adjectives both morphologically and syntactically.

The current–voltage characteristics of modern electronic devices consisting of semiconductor heterostructures, such as resonant tunneling diodes, quantum cascade lasers, and tandem solar cells, are determined by the dynamics of electrons propagating through quantum-engineered 1D potential landscapes. In this chapter, we will develop a general formalism with which to describe transmission probabilities for electron waves propagating through arbitrary potentials, which can be used for analyzing electron motion in semiconductor devices. Furthermore, we will extend our formalism to 1D electrons moving in a general spatially periodic potential, based on which we will describe the basic concepts of the band theory of solids. The central theorem in band theory is the Bloch theorem, which we will derive and then use for discussing the dynamics of electrons in crystalline solids (or Bloch electrons).