Statistics Random Data
This chapter is about statistics random data and numerical data.
a branch of mathematics dealing with the collection, analysis, interpretation and presentation of masses of numerical data
organizes, presents, summarizes: graphically, numerically, pictorially..convenient and informative, simplifies comparisons
estimates, predicts, decides, draw conclusions or inferences, USES SMALLER AMOUNTS OF DATA
is the group (individuals,items, measurements) of interest which is usually not easy to access directly
describes some characteristics of the population. paramaters are usually unknown
a part of the population that we actually examine and for which we collect data. it is smaller (sometimes more accessible) group
is a number that describes a characteristic of a sample. often, a sample is used to estimate an unknown parameter
the process of making an estimate, prediction, or decision about a population based on a sample
tells the proportion of time that our conclusion will be correct
a numerical measure of how often a result will be wrong
a characteristic of a population or sample of interest
real numbers..heights weights prices- quantitative or numerical histograms
qualitative or categorical. the values of nominal data are categories. ex: single=1 married=2 pie charts and bar graphs
values have an order a ranking to them. order is maintained no matter what numeric values are assigned.
used to display frequencies
the bar represents each category, height of the bar represents the frequency
the base of the bar is arbitrary
shows relative frequencies. the pies represent categories.
histogram stem and leaf and ogive
are used when the data is interval
used to describe the relationship between two nominal variables. lists the frequencies of each combination of the values of the two variables. the data can then be summarized in a bar cart graphically
two interval variables related?
scatter diagram or scatterplot
predictor, explanatory- stays the same. is labeled x on the horizontal axis
is the outcome or the response and is labeled y on the vertical axis
one nominal and one interval
bar chart is an effective way to summarize this.
time series plot
observations measured at successive points in time.graphed on a line chart. time periods go on the horizontal axis
average. appropriate for describing interval data.
mean for a sample
mean for a population
appropriate for interval or ordinal data. best for data dealing with extreme values. computed the same for population and sample. (n+1)/2
occurs most frequently. useful for all data mainly for identifying the group with the highest frequency for nominal data
used when the variable is a growth rate of change.
largest observation-smallest observation
population- sigma squared
square root of the variance
data that is collected at a certain point in time. starting salaries of mba students.
is collected over a period of time. weekly starting prices of gold.
collected from the current point in the future
retrospective or historical
collected on events that have happened in the past.
the process of selecting a subset of a whole population. cost efficient. and practical. the sample and the target population should be similar to each other.
a method or procedure for specifying how a sample will be taken from a population.
everyone has an equal chance of being selected
separating the population into mutually exclusive set. split into groups first and then use random sampling
a simple random sample of groups or clusters. may increase error