Ch. 1

Sample

a set of individuals selected from a population, usually intended to represent the population with in a research study

parameter

a value that describes a population

statistic

a value that describes a sample

Population

an entire set of individuals of interest for a particular research question

What is the goal for an experimental research study? Identify the two elements that are necessary for an experiment to achieve its goal.

Goal: demonstrate a cause-effect relationship between two variables. 1. manipulation: one variable is changed (independent variable) 2. control: one variable remains constant (dependent variable)

Judge and Cable (2010) found that thin women had higher incomes than heavier women. Is this an example of an experimental or nonexperimental study?

Nonexperimental study, b/c neither variables are being manipulated, just observed.

Explain why shyness is a hypothetical construct instead of a concrete variable. Describe how shyness might be measured and defined using an operational definition.

Shyness is a hypothetical construct b/c it is an internal attribute that cannot be directly observed but is useful for describing/explaining behavior. An operational definition measures and defines a construct in terms of external behaviors. (test levels of shyness, then use scores to define)

For the following set of scores, find the value of each expression: X= 6, -2, 0, -3, -1 a. EX b. EX^2 c. E(X+3)

a.) 0 b.) 50 c.) 15

For the following scores, find the value of each expression: X= 3, 5, 0, 2 a. EX b. EX^2 c. EX+1 d. E(X+1)

a.) 10 b.) 38 c.) 11 d.) 14

Use summation notation to express each of the following calculations: a.) add 1 point to each score, and then add the resulting values b.) add 1 point to each score and square the result. Then add the squared values c.) Add the scores and square the sum. Then subtract 3 points from the squared value.

a.) E(X+1) b.) E(X+1)^2 c.) (EX)^2 -3

Four scales of measurement were introduced in this chapter: nominal, ordinal, interval, and ratio a.) What additional information is obtained from measurements on an ordinal scale compared to measurements on a nominal scale? b.) What additional information is obtained from measurements on an interval scale compared to measurements on an ordinal scale? c.) What additional information is obtained from measurements on a ratio scale compared to measurements on an interval scale?

a.) With measurements from an ordinal scale, you can determine whether 2 individuals are different and the direction (magnitude) of differences. b.) An interval scale has ordered categories of all the same size, as well as an arbitrary zero point. c.) A ratio scale is an interval scale with an absolute zero point (meaningful zero point).

Weinstein, McDermott, and Roediger (2010) conducted an experiment to evaluate the effectiveness of different study strategies. One part of the study asked student to prepare for a test by reading a passage. In one condition, students generated and answered questions after reading the passage. In a second condition, students simply read the passage a second time. All students were then given a test on the passage material and the researchers recorded the # of correct answers. a.) identify the dependent variable b.) in the dependent variable discrete or continuous? c.) what scale of measurement is used to measure the dependent variable?

a.) dependent variable = the effectiveness of study strategies based by the # of correct answers on a test (the different study strategies used) b.) discrete: finite and countable # of questions c.) ratio scale

Define the concept of sampling error, and explain why this phenomenon creates a problem to be addressed by inferential statistics.

the naturally occuring discrepancy, or error, between a sample and population parameter. The percentages from a sample are often used to represent an entire population. Every sample is different, b/c of natural differences in the population. This means not one set of data can be 100% correct in defining the entire population.