1 Chapter 1
what are 4 scales of measurement
Nominal scale, ordinal scale, interval scale and ratio scale
statistic
(fraction) is a numerical measurement describing some characteristic of a sample. it is usually derived from measurements of the individual in the sample..... numbers that summarize data from a sample.
parameter
(whole population) is a value, usually a numerical value, that describes a population. A parameter is usually derived from measurements of the individuals in the population..... parameters are numbers that summarize data for an entire population.
Control condition
individuals in this condition do not receive the experimental treatment. instead, they either receive no treatment or they receive a neutral, placebo treatment. The purpose of a control condition is to provide a baseline for comparison with the experimental condition.
Independent variable
is the variable that is manipulated by the researcher. In behavioral research, the independent variable usually consists of the two ( or more treatment conditions to which subjects are exposed. the independent variable consists of the antecedent conditions that were manipulated prior to observing the depend variable.
Correlational method
two different variables are observed to determine whether there is a relationship between them.... is a quantitative method of reach in which you have 2 or more quantitative variables from the same group of subjects and you are trying to determine if there is a relationship or covariation between the 2 variables.
upper real limit
upper real limit is at the top of the interval. The boundary of a score that is exactly half way between this score and the next score.
Constructs:
Constructs: are internal attributes or characteristics that cannot be directly observed but are use full for describing and explaining behavior. variables like intelligence, anxiety, and hunger are called constructs, and because they are intangible and cannot be directly observed they are often called hypothetical constructs........variables like happiness or intelligence, are called constructs and need have an operational definition.
ordinal level of measurement
involves data that may be arranged in some order, but differences between data values either cannot be determined or are meaningless.... Consists of a set of categories that are organized in an order sequence. measurements on an ordinal scale rank observations in terms of size or magnitude. often consists of a series of ranks (first, second, third and so on) like order of finish in a horse race occasionally, the categories are defied by verbal labels like small, medium and large drink sizes at a fast food restaurant. Ordinal measurements do not allow you to determine the size of the difference between two individuals. if bill placed in low reading group and tim is placed in the high reading group you know that time is better reader, but you don't how much better
Statistics
is a collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions based on the data.
nominal level of measurement
is characterized by data that consist of names, labels, or categories only. The data cannot be arranged in an ordering scheme (such as low to high).
Experimental conditions
one variable is manipulated while another variable is observed and measured to see how it changes. to establish a cause-and effect relationship between the two variables, an experiment attempts to control all other variables to prevent them from influencing the results... In particular, a real experiment must include manipulation of an independent variable and rigor control of other, extraneous variables.....
Random assignment
which means that each participant has an equal chance of being assigned to each of the treatment conditions. The participant characteristics evenly between the two groups so that either group is noticeably smaller ( or older, or faster) than the other.
Inferential statistics
(interpret results) consist of techniques that allow us to study samples and then make generalizations about the populations from which they were selected...... explains how your results relate to the population ( what predicts whether or not people are happier commuting or driving). Because samples are not perfect representations of the population, your data will always have sampling error.
Descriptive statistics
(organize and simplify) are statistical procedures used to summarize, organize and simplify data..... summarize your results ( how many people were interviewed, what was the average answer and so on)
Real limits
are the boundaries of intervals for scores that are represented on a continuous number line. the real limit separating two adjacent scores is located exactly halfway between the scores. each score has two real limits.
Variable
are things that vary like one person using public transportation and another driving. Research examines the relationship between two or more variables. to find out whether one's choice of transportation affects happiness.
Discrete variable
consists of separate, indivisible categories. For this types of categories, there are no intermediate values between two adjacent categories. EX: if you observe class attendance from day to day, you may count 18 a students one day. However , it is impossible ever to observe a value between 18 and 19. it must be whole number discrete variable may consist of observations that different qualitatively, people classified by gender (male or female), by occupation ( nurse, teacher) and college student. variables have values that separate and cane be expressed in categories or whole umbers ( biological sex: M or F ; number of children).
Quasi-independent variable
independent variable in non-experimental study are often called quasi-independent. This independent variable that is used to create the different groups of scores.
Sampling Error
is the naturally occurring discrepancy, or error that exists between a sample statistic and the corresponding population parameter.
Continuous variable
there are an infinite number of possible values that fall between any two observed values. A continuous variable is divisible into an infinite number of fractional parts. 1. it should be very fare to obtain identical measurements for two different individuals. 2. each measurement category is actually an interval that must be defined by boundaries.....Continuous variable has an infinite number of possible values and can be represented by a number line that is continuous and contains an infinite number of points. ex: 2 people who both claim to weigh 150 pounds are probably not exactly the same weight............ variables do not have discrete values because they can be divided in to smaller and smaller parts (time, hight, weight).
Operational definition
identifies a measurement procedure (a set of operations) for measuring an external behavior and uses the resulting measurements as a definition and a measurement of a hypothetical construct. note that an operational definition has two components: First, it describes a set of operations of r measuring a construct . Section, it defines the construct in terms of the resulting measurements. defines a construct in terms of external behaviors that can be observed and measured.......to obtain an operational definition for a construct means to come up with a way to measure it and have the results contribute to its definition. EX: happiness can be described throughs a series of statements (i feel good most days") and these statements can be the basis of a survey.
sample
is a set of individuals selected from a population, usually intended to represent the population in a research study. It is intended to be representative of its population, and it should always be identified in terms of the population from which it was selected..... consists one or more observations drawn from the population.
interval level of measurement
is like the ordinal level, with the additional property that we can determine meaningful amounts of differences between data. However, there is no inherent (natural) zero starting point (where none of the quantity is present).......consists of ordered categories that are all intervals of exactly the same size. equal differences between numbers on a scale reflect equal differences in magnitude. However, the zero point on an interval scale is arbitrary and does not indicate a zero amount of variable being measured........ there is no true zero. a set of ordered values that are separated by intervals of exactly the same size, without a true zero. example: 0 degree C or cows hight......... the interval/ratio scales consist of ordered categories that have equal intervals ex: could be a variable titled ' Temperature' and you know that the interval is always 1 degree......Here's the problem with interval scales: they don't have a "true zero." For example, there is no such thing as "no temperature." Without a true zero, it is impossible to compute ratios. With interval data, we can add and subtract, but cannot multiply or divide. Confused? Ok, consider this: 10 degrees + 10 degrees = 20 degrees. No problem there. 20 degrees is not twice as hot as 10 degrees, however, because there is no such thing as "no temperature" when it comes to the Celsius scale.
population
is the complete collection of all elements (scores, people, measurements, and so on) to be studied.
sampling error
is the difference between a sample result and the true population result; such an error results from chance sample fluctuations.
ratio level of measurement
is the interval level modified to include the inherent zero starting point (where zero indicates that none of the quantity is present). For values at this level, differences and ratios are both meaningful.....is an interval scale with the additional feature of an absolute zero point. With a ratio scale, ratios of numbers do reflect ratios of magnitude. Ratio scale is the nature of the zero point. A set of ordered values that are separated by intervals of exactly the same size, with a true zero. example would be kelvin. this has true zero.........Ratio scales provide a wealth of possibilities when it comes to statistical analysis. These variables can be meaningfully added, subtracted, multiplied, divided (ratios).
Dependent variable
is the variable that is observed to assess the effect of the treatment. The variable that is observed and measured to obtain scores within each conniption is the dependent variable.
lower real limit
lower real limit is at the bottom. . EX: a score of X= 150 pounds is actually an interval bounded by a lower real limit of 149.5 at the bottom and an upper real limit of 150.5 at the top.... the boundary of a score that is exactly half way between this score and the preceding score
Nominal scale:
means having to do with names. Nominal scales are used or labeling variables, without any quantitative value. EX: if you were measuring the academic majors for a group of college students, the categories would be at, biology business , history and so on..... consists of a set of categories that have different names. Measurements on a nominal scale label and categorize observations, but do not make any qualitative distinctions between observations........ a set of separate categories that all belong to one common concept and do not follow any specific order.........A nominal scale should be used when you have set of categories ex: variable titled religion where you may have 4 categories: Christian, Jewish, Muslim and Atheist.
random sample
members of the population are selected in such a way that each individual has an equal chance of being selected.
simple random sample
of n subjects is selected in such a way that every possible sample of size n has the same chance of being chosen.
Experimental method
one variable is manipulated while another variable is observed and measured to see how it changes. to establish a cause-and effect relationship between the two variables, an experiment attempts to control all other variables to prevent them from influencing the results... In particular, a real experiment must include manipulation of an independent variable and rigor control of other, extraneous variables.....
experiment
we apply some treatment and then proceed to observe its effects on the subjects.
observational study
we observe and measure specific characteristics, but we don't attempt to manipulate or modify the subjects being studied.