82 terms

Sampling

process of obtaining information from a subset of a larger group

population

entire group of people about whom information is needed; also called universe or population of interest.

census

collection of data obtained from or about every member of the population of interest

sample

subset of all the member of a population of interest

sampling frame

list of population elements from which units to be sampled can be selected or a specified procedure for generating such a list

random digit dialing

method of generating lists of telephone numbers at random

probability sample

samples in which every element of t he population has a known nonzero likelihood of selection

non probability sample

samples in which specific elements from the population have been selected in a nonrandom manner

sample size

the identified and selected population subset for the survey, chosen because it represents the entire group

n = (Z^2)(SD^2) / SE^2

n = (Z^2)(SD^2) / SE^2

population parameter

a value that accurately portrays or typifies a factor of a complete population, such as average age or income

sampling error

error that occurs because the sample selected is not perfectly representative of the population

non sampling error

all errors other than sampling error; also called measurement error

simple random sample

probability sample selected by assigning a number to every element of the population and then using a table of random numbers to select specific elements for inclusion in the sample

systematic sampling

probability sampling in which the entire population is numbered and elements are selected using a skip interval

stratified sample

probability sample that is forced to be more representative through simple random sampling of mutually exclusive and exhaustive subset

proportional allocation

sampling in which the number of elements selected from a stratum is directly proportional to the size of the stratum relative to the size of the populations

disproportional (optimal) allocation

sampling in which the number of elements taken from a given stratum is proportional to the relative size of the stratum and the standard deviation of the characteristic under consideration.

cluster sample

probability sample in which the sampling units are selected from a number of small geographic areas to reduce data collection costs

multistage area sampling (multistage area probability sampling)

geographic areas selected for national or regional surveys in progressively smaller population units, such as counties, then residential blocks, then homes

convenience samples

non probability samples based on using people who are easily accessible

judgment sample

non probability sample in which the selection criteria are based on the researcher's judgment about representativeness of the population under study.

quota samples

non probability samples in which quotas, based on demographic or classification factors selected by the researcher, are established for population subgroups

snowball samples

non probability samples in which additional respondents are selected based on referrals from initial respondents

central limit theorem

idea that a distribution of a large number of sample means or sample proportions will approximate a normal distribution, regardless of the distribution of the population from which they were drawn

normal distribution

continuous distribution that is bell shaped and symmetric about the mean; the mean, median, and mode are equal.

proportional property of the normal distribution

feature that the number of observations falling between the mean and a given number of standard deviations from the means is the same for all normal distribution

standard normal distribution

normal distribution with a mean of zero and a standard deviation of one

standard deviation

measures of dispersion calculated by subtracting the mean of the series from each value in series, squaring each result, summing the results, dividing the sum by the number of items minus 1, and taking the square root of this value.

population distribution

frequency distribution of all the elements of a population

sample distribution

frequency distribution of all the elements of an individual sample

sampling distribution of the mean

theoretical frequency distribution of the means of all possible samples of a given size drawn from a particular population; it is normally distributed.

standard error of the mean

standard deviation of a distribution of sample means

SD/Sqroot(n)

SD/Sqroot(n)

point estimate

particular estimate of a population value

interval estimate

interval or range of values within which the true population value is estimated to fall

confidence level

probability that a particular interval will include true population value; also called confidence coefficient

confidence interval

interval that, at the specified confidence level, includes the true population value

sampling distribution of the proportion

relative frequency distribution of the sample proportions of many random samples of a given size drawn from a particular population; it is normally distributed

allowable sampling error

amount of sampling error the researcher is willing to accept

population standard deviation

standard deviation of a variable for the entire population

independence assumption

assumption that sample elements are drawn independently

finite population correction factor

an adjustment to the required sample size that is made in cases where the sample is expected to be equal to 5 percent or more of the total population

statistical power

probability of not making a type 2 error

validation

process of ascertaining that interviews actually were conducted as specified.

editing

process of ascertaining that questionnaires were filled out properly and completely

skip pattern

sequence in which later questions are asked based on a respondent's answer to an earlier question or questions.

coding

process of grouping and assigning numeric codes to the various responses to a question

data

process of converting information to an electronic format.

intelligent data

form of data in which the information being entered into the data entry device is checked for internal logic.

scanning technology

form of data entry in which responses on questionnaires are read in automatically by the data entry device

logical or machine cleaning of data

final computerized error check of data

error checking routines

computer programs that accept instructions from the user to check for logical errors in the data

one way frequency table

tables showing the number of respondents choosing each answer to a survey question

cross tabulations

examination of the responses to one question relative to the responses to one or more other questions

mean

sum of the values for all observations of a variable divided by the number of observations.

median

value below which 50 percent of the observations fall

mode

values that occurs most frequently

statistically significant

a difference that is large enough that it is not likely to have occurred because of chance or sampling error.

hypothesis

assumption or theory that a researcher or manager makes about some characteristics of the population under study.

null hypothesis

the hypothesis of status quo, no difference, no effect

decision rule

rule or standard used to determine whether to reject or fail to reject the null hypothesis

type 1 error

rejection of the null hypothesis when, in fact, it is true (a error)

type 2 error

failure to reject the null hypothesis when, in fact, it is false (B error)

p value

exact probability of getting a computed test statistic that is due to chance. the smaller the P value, the smaller the probability that the observed result occurred by chance.

correlation analysis

analysis of the degree to which changes in one variable are associated with changes in another.

pearson's product moment correlation

a correlation analysis technique for use with metric data

regression analysis

a procedure for predicting the level or magnitude of a (metric) dependent variable based on the level of multiple independent variables.

coefficient of determination

a measure of the percentage of the variation in the dependent variable explained by variations in the independent variables.

regression coefficient

estimates of the effect of individual independent variables on the dependent variable

dummy variables

in regression analysis, a way of representing two - group or dichotomous, nominally scaled independent variables by coding one group as 0 and the other as 1.

collinearity

the correlation of independent variables with each other, which can bias estimates of regression coefficient.

causation

inference that a change in one variable is responsible for (caused) an observed change in another variable

scaling of coefficients

a method of directly comparing the magnitudes of the regression coefficients of independent variables by scaling them in the same units or by standardizing the data.

cluster analysis

a general term for statistical procedures that classify objects or people into some number of mutually exclusive and exhaustive groups on the basis of two or more classification variables

factor analysis

a procedure for simplifying data by reducing a large set of variables to a smaller set of factors or composite variables by identifying underlying dimensions of the data

factor

a linear combination of variables that are correlated with each other

factor loadings

correlation between factor scores and the original variables

conjoint analysis

a procedure used to quantify the value t hat consumers associated with different levels of product/service attributes or features.

utilities

the relative value of attribute levels determined through conjoint analysis

executive summary

portion of a research report that explains why the research was done what was found, what those findings mean and what action, if any, management should undertake

conclusions

generalizations that answer the questions raised by the research objectives or other wise satisfy the objectives

recommendations

conclusions applied to marketing strategies or tactics that focus on a client's achievement of differential advantage.

research management

overseeing the development of excellent communication systems, data quality, time schedules, cost controls, client profitability, and staff development