qba 237 test 1

discrete

(quantitative) if it can assume only a finite or countable number of values

continuous

(quantitative) if it can assume the infinitely many values corresponding to the points on a line interval

variable

a characteristic of interest for the elements

variable

a characteristic that changes or varies over time and/or for different individuals or objects under consideration

skewed right

a few unusually large measurements

skewed left

a few unusually small measurements

measures of variability

a measure along the horizontal axis of the data distribution that describes the spread of the distribution from the center

parameter

a numerical descriptive measure calculated for a population

statistic

a numerical descriptive measure calculated for a sample

random sampling

a procedure for selecting a subset of the population units in such a way that every unit in the population has an equal chance of selection. since the validity of all statistical results depend upon the original sampling process, it is essential that this process is "blind". this implies that every element in the population is equally likely to be selected for the sample without bias

pie or bar chart

a single quantitative variable measured for different population segments or for different categories of classification can be graphed using this

time series

a single quantitative variable measured over time

sample

a subset of the population

production

a variety of statistical quality control charts are used to monitor the output of a production process

nominal

data are labels or names used to identify an attribute of the element; a nonnumeric label or a numeric code may be used (students classified by school-business, humanities, education)

range

difference between the largest and smallest measurements

economics

economists use statistical information in making forecasts about the future of the economy or some aspect of it

marketing

electronic point-of-scale scanners at retail checkout counters are being used to collect data for a variety of marketing research applications

finance

financial analysts use a variety of statistical information, including price-earnings ratios and dividend yields, to guide their investment recommendations

relative frequency histogram

for quantitative data set, a bar graph in which the height of the bar shows "how often" (measured as a proportion or relative frequency) measurements fall in a particular class or subinterval

z-score

how many standard deviations away from the mean does the measurement lie

scales of measurement

include nominal, ordinal, interval, ration; determines the amount of information contained in the data; indicated the data summarization and statistical analyses that are most appropriate

quantitative data

indicate either how many or how much; always numeric

qualitative data

labels or names used to identify an attribute of each element; nominal or ordinal scale of measurement

skewed left

mean<median

symmetric

mean=median

skewed right

mean>median

quantitative variables

measure a numerical quantity on each experimental unit

qualitative variables

measure a quality or characteristic on each experimental unit

variance

measure of variability that uses all the measurements. it measures the average deviation of the measurements about their mean

mode

measurement which occurs most frequently

discrete

measures how many

continuous

measures how much; no separation between the possible values for the data

multivariate data

more than two variables are measured on a single experimental unit

univariable data

one variable is measured on a single experimental unit

accounting

public accounting firms use statistical sampling procedures when conducting audits for their clients

measurement

results when a variable is actually measured on an experimental unit

descriptive statistics

tabular, graphical, and numerical methods used to summarize data

ratio

the data have all the properties of interval data and the ratio of two values is meaningful; distance, height, weight, time; scale must contain a zero value that indicates that nothing exists for the variable at the zero point (36 credit hours, 72 credit hours)

ordinal

the data have the properties of nominal data and the order or rank of the data is meaningful; a nonnumeric label or a numeric code may be used; (student classified as freshman, sophomore, junior, senior)

interval

the data have the properties of ordinal data and the interval between observations is expressed in terms of a fixed unit of measure; always numeric; (SAT score of 1205, 1090)

elements

the entities on which data are collected

data

the facts and figures that are collected, summarized, analyzed, and interpreted

experimental unit

the individual or object on which a variable is measured

median

the middle measurement when the measurements are ranked from smallest to largest (.5(n+1)

interquartile range (IQR)

the range of the "middle 50%" of the measurements

population

the set of all elements of interest in a particular study

mean

the sum of the measurements divided by the total number of measurements

lower quartile (Q1)

the value of x which is larger than 25% and less than 75% of the ordered measurements; =.25(n+1)

upper quartile (Q3)

the value of x which is larger than 75% and less than 25% of the ordered measurements;=.75(n+1)

standard deviation

to return a measure of variability to the original units of measure; the positive square root of the variance

bimodal

two local peaks

bivariate data

two variables are measured on a single experimental unit