Exam 1: An Introduction to Statistics and Research Design

A reliable measure:

A test with poor validity cannot have good reliability.

A sample is generally defined as:

Descriptive statistics summarize a group, while inferential statistics help us make estimates about a larger population.

An elementary school teacher is interested in the relation between sugar consumption and activity level in preschool children.The teacher gives 30 preschool children from Preppy Preschool Playland 0 milligrams, 20 milligrams, or 50 milligrams of sucrose (sugar) in a breakfast drink.She then observes their behavior for 30 minutes during their morning outdoor play period and codes their activity level.In this example, the dependent variable is:

In a within-groups research design, a participant experiences only one of the levels of the dependent variable.

Clayton has a history of depression.As part of his self-care, he takes a depression assessment every six months.His results tend to be very consistent, except when he is in a serious depression and his results show elevated levels of depression.The tendency for his results to be consistent supports the _____ of the assessment.

The United States Department of Homeland Security Threat Advisory System measures threat as severe, high, elevated, guarded, or low.In this system, threat is:

Continuous observations can typically take on more values than discrete observations.

People debate whether standardized tests, such as the ACT and SAT, are predictors of college performance.This is essentially a debate about:

A New York Times article published on April 24, 2007, reported the research of Dr.Vallortigara, a neuroscientist at the University of Trieste, Italy.In this study, Dr.Vallortigara assessed whether a dog's tail wags in a preferred direction in response to positive as opposed to negative stimuli.First, Dr.Vallortigara recruited 30 dogs that were family pets.While filming a dog's tail from above, he allowed the dog to view (through a slot in its cage) its owner, an unfamiliar human, a cat, and an unfamiliar dominant dog.The study found that dogs' tails wagged to the right for the owner and to the left for the unfamiliar dominant dog.What type of measure was the independent variable in this study?

A medical researcher interested in asthma symptoms wanted to know how symptoms were affected in dry versus humid conditions.The researchers recruited 18 asthma patients to spend four weeks under two conditions: sleeping with a dehumidifier for two weeks to create a "dry" environment and sleeping with a humidifier for the remaining two weeks to create a "humid" environment.Patients were asked to rate their symptoms at regular intervals using a scale from "0 - no symptoms" to "20 - maximum asthma symptoms." The change in asthma symptoms from dry to humid conditions was 5.82, showing a reduction of symptoms in humid conditions.What is MOST likely the population of interest for this researcher?

Imagine that a variable "sensitivity to others" is measured from 10 (low) to 80 (high).Although it is possible to have low sensitivity to others, it is not conceptually possible to have no sensitivity at all.What type of variable is this MOST likely to be?

A researcher studies length of time in college, first through fourth year, and its relation to academic motivation.To get the most detail out of her measures, she assesses each student in both the fall and spring semesters of each of their four years in school.She finds that students have increasingly higher motivation from their first semester to their seventh semester (the start of their fourth year), with a trailing off in the last semester.What is the independent variable in this study?

Appropriate treatment of outliers can involve:

Eye color, assessed as blue, green, hazel, brown, and other, as a variable is measured on a(n) _____ scale.

An operational definition is one that:

The outcome variable that we expect to change with changes in the independent variable is the _____ variable.

A researcher wanted to determine whether eating sugary cereal for breakfast increased the aggression of second graders during their morning play period.After feeding a group of 20 students sugary cereal for breakfast she observed that, on average, the students committed 4.5 aggressive behaviors during their morning play period.In this example, the descriptive statistic is:

Outlier analysis involves: