Exam 1: The Role of Statistics and the Data Analysis Process

In a psychological study of distance perception, introductory psychology class volunteers were given 5, 10, or 15 extra credit points depending on their level of participation in the experiment.They walked along paths laid out along hallways in the psychology building, and were asked to judge the distance they had walked.Each path distance was between 100 and 200 feet in length, and contained from two to seven 90 degree turns.The investigators also kept track of class standing (freshman, sophomore, junior, or senior).For each of the variables in this study, determine whether it is categorical or numerical.For each numerical variable, determine whether it is discrete or continuous:

In a study of how college students give directions from maps, 40 Introductory Psychology volunteers, 20 men and 20 women, were given the task of giving directions to another.Observations were made of subjects' direction-giving behavior in the experiment:

Dotplots work best for small and moderate sized numerical data sets.

Briefly describe how inferential and descriptive statistics differ.

Biologists know that bats have different flight characteristics.Some bats exhibit fast, straight, and long flights; others are moderately slow, and highly maneuverable.The flight capabilities of bats are presumably a function of (a)the characteristics of the bat wings, and (b)the laws of physics.The data presented below are wing weights in grams for certain species of bats from Nicaragua and Costa Rica.Two categories of bat species are represented: fruit-eaters and insect-eaters.

Artificial nest have often been used when biologists study predation on birds.It is usually assumed that predators will respond to artificial nests in the same way they do to real birds' nests.A recent experiment was performed to check this assumption for predators of the American robin (Turdus migratorius)by comparing the egg loss in three experimental treatments: (1)natural robin's nests, (2)artificial wicker-basket nests placed 30 meters in a random direction from natural robin's nests, and (3) artificial wicker-basket nests placed in a 180 m by 240 m grid around robin's nests. The data below are cumulative counts of eggs predated (stolen or broken and eaten)at 5, 10, and 15 day points of the experiment.

Methods for summarizing data make up the branch of statistics called inferential statistics.

Frequency distributions can only be used with categorical data.

A data set consisting of many observations of a single characteristic is a categorical data set.

The most important right and responsibility of citizens in a democratic society is voting.The bar chart below shows, for different age groups in the 2000 presidential election in the United States, the percentage of individuals in that age group who are registered to vote.

A data set is discrete if the possible values are isolated points on the number line.

The relative frequency for a particular category is the number of times the category appears in the data.

The entire collection of individuals or objects about which information is desired is called a sample.

The most important right and responsibility of citizens in a democratic society is voting.The bar chart below shows, for different age groups in the 2000 presidential election in the United States, the percentage of individuals in that age group who actually voted.

Bat characteristics Biologists know that bats have different flight characteristics.Some bats exhibit fast, straight, and long flights; others are moderately slow, and highly maneuverable.The flight capabilities of bats are presumably a function of (a)the characteristics of the bat wings, and (b)the laws of physics.The data presented below are wing spans in centimeters for certain species of bats from Nicaragua and Costa Rica.Two categories of bat species are represented: fruit-eaters and insect-eaters.

Briefly describe how populations and samples differ.

Bird-plane collisions Collisions between birds and airplanes are a major problem, threatening passenger safety and resulting in costly repairs.During the years 1990 - 1994, researchers gathered bird remains from runways at Lihue Airport on the island of Kauai, Hawaii.The data below are counts of birds found on the runway used for takeoffs and the runway used for landings from the 4 most frequently involved species:

A primary use of inferential statistics is to make generalizations from a sample to a population.

Bar charts should be used with categorical data.

A data set is multivariate if it consists only of numeric variables.