#### ISDS 2001 - Exam One LSU

The branch of mathematics that uncovers patterns in data and transforms that into useful information for decision making

Statistics

Those methods involved in the collection, summarizing, presenting, and analyzing a set of data in order to describe the various features of that data set.

Descriptive Statistics

What are these items an example of: Creating pie charts, histograms; calculating mean, median, mode, reporting unemployment rate, DJIA, crime rate, the number of freshmen entering LSU this past fall, median home values

Descriptive Statistics

Those methods that use data from a smaller group (sample) to make conclusions/decisions about the characteristic of a larger group (population)

Inferential Statistics

The entire set of observations for which conclusions are to be made

Population

A subset of the population selected for analysis

sample

a summary measure that describes a characteristic of an entire population (� or ?)

Parameter

a summary measure that describes a characteristic of a sample

statistic

A 2010 survey of 1,208 registered voters by a USA Today/Gallup Poll found that President Obama's job performance was viewed as favorable by only 41% of those polled, the lowest rating since he took office in January 2009.
What is the population?

The population consists of all registered voters

A 2010 survey of 1,208 registered voters by a USA Today/Gallup Poll found that President Obama's job performance was viewed as favorable by only 41% of those polled, the lowest rating since he took office in January 2009.
What is the sample?

The sample consists of the 1208 voters surveyed

A 2010 survey of 1,208 registered voters by a USA Today/Gallup Poll found that President Obama's job performance was viewed as favorable by only 41% of those polled, the lowest rating since he took office in January 2009.
What is the sample statistic?

The sample statistic is the 41% and is used to estimate the population parameter

A 2010 survey of 1,208 registered voters by a USA Today/Gallup Poll found that President Obama's job performance was viewed as favorable by only 41% of those polled, the lowest rating since he took office in January 2009.
What is the population parameter?

The population parameter is the percentage of all registered voters viewing President Obama's job performance as favorable, is unknown

We use the _______ to make inferences about the population because we generally do not have information for the entire population

sample

What are the two reasons for sampling?

1. Studying the entire population is expensive
2. It is impossible to examine every member of the population

What are the two types of data?

Cross-sectional and Time Series

This type of data is data collected at one point in time

Cross Sectional

This type of data is data collected over several periods of time

Time series data

The characteristic of an observation or individual

Variable

The values associated with a variable

Data

What are the two types of variables?

Categorical and Quantitative

This type of variable has values that can be placed into categories

Categorical variables

Yields values that represent quantities

Quantitative Variables

Result of counting

Discrete

Measurements can take on infinitely many values within an interval

Continuous

A tabular summary of a data showing the frequency of items in each of the distinct categories

Frequency Table

A graphical display of data where each category is depicted by a bar representing the frequency or proportion of observations in that category

Bar Graph

A graphical display of data where slices of the pie in degrees are associated with the frequency or proportion of observations in that category

Pie Chart

Average; value around which observations tend to cluster; balance point of a histogram

Mean

The middle value of an ordered array

median

The observation number that occurs most often

Mode

Largest Value - Smallest Value; influenced by outliers

Range

The measure of variability that utilizes all data values. A measure that reflects how observations vary or deviate from the mean.

Variance

The square root of variance

standard deviation

Both population and sample variances and standard deviations are influenced by ________

outliers

Both variances and standard deviations are either _______ or _______

zero or positive

As data becomes more concentrated , variance and standard deviation __________

decreases

Data where all values are the same have ______ variation

no

The manner in which data are distributed

shape

A distribution in which one half of the data are a mirror image of the other half

symmetrical distribution

a distribution which is asymmetric

skewed distribution

Always: mode < mean
Always: mode < median
Most of the time: mode < median < mean

right skewed

Always: mean < mode
Always: median < mode
Most of the time: mean

left skewed

The initial statement about the population and ordinarily represents a commonly accepted state of affairs, a general position or the status quo.

null hypothesis

The ________ is tentatively believed to be true unless overwhelming refuted by data

null hypothesis

Represented by H0

null hypothesis

Is the opposite of the null hypothesis and corresponds to what the researcher wants to prove

Alternative Hypothesis

Represented by H1

Alternative Hypothesis

If we reject the null hypothesis when in reality the null hypothesis is true, we commit a ________ error, where the probability of making a ________ error is denoted by ?.

Type I

The process of using sample statistics to draw conclusions about the population parameters is called

statistical inference

A summary measure that is computed to describe a characteristic of a sample taken from a population is called

statistic

Viewership studies using a sample of the television households indicate that the share of the audience for the channel 9 news has increased by 12% since the new anchor was added to the 10:00pm news team. this is an example of ______

inferential statistics

You are reviewing your portfolio and note the amount of interest earned for each of the sticks in which you have invested. The type of variable most appropriate to their measurements is

numeric, continuous

When constructing a frequency distribution which of the following is true?
A. the class midpoint is the number of observations that fall within that class
B. There should always be at least 10 classes
C. The classes do not overlap

C. The classes do not overlap

The department of transportation estimates that there is an average 20 accidents per day. This is an example of

statistical inference