Data Analytics - Exam 1

sample mean equation

(= ∑x ÷ n) (notation called x-bar)

steps to analyze data

1. recognize a problem that needs to be solved (sales going down) 2. gather the data 3. analyze it 4. act on this analysis by changing policies

samples should be

1. representative of the population 2. randomly chosen

Of these 1,000 customers, how many are married males at least 60 years old with salaries exceeding $125,000?

26

If a value represents the 95th percentile, this means that:

95% of all values are below this value

quartile

A division of the total into four intervals, each one representing one-fourth of the total.

measure of central tendency

A number that describes roughly where the data are located or centered along the number line

categorical data

Data that consists of names, labels, or other nonnumerical values

Examples of ordinal data

Rate your pain on a scale of 10 1 - good 2 - ok 3 - bad

percentile

Specific point in a distribution of data that has a given percentage of cases below it.

mode

The value that occurs most frequently in a given data set

True or False: A variable (or field or attribute) is a characteristic of members of a population, whereas an observation (or case or record) is a list of all variable values for a single member of a population

True

True or False: Age, height, and weight are examples of numerical data

True

measure of location

When describing numerical data, it is common to report a value that is representative of the observations in the data set

panel data

a combination of cross-sectional and time series *most desirable*

data set

all the data collected in a particular study

median is often used for

annual wages

data

are the facts and figures (text, voice ...) collected, analyzed and summarized for presentation and interpretation

mean

average of all the data values *central location*

if data has two modes, the data is

bimodel

statistics

can be referred to the art and science of collecting, analyzing, presenting, and interpreting data

Gender and states of residence are examples of

categorical data

qualitative

categorical data: classify subjects into two categories

to present data, we use:

charts numerical summary (% , avg.) tables of summary measures

structure of data

cross sectional time series panel data

cross-sectional data

data collected at the same or approximately the same point in time

time series data

data collected over several time periods

examples of nominal data

gender hair color where you live religion

The average score for a class of 30 students was 75. The 20 male students in the class averaged 70. The 10 female students in the class averaged:

higher than the males

The difference between the first and third quartile is called the:

interquartile range

example of coding categories

marital status dumby variable

most common central tendencies

mean median mode percentile quartile

descriptive statistics

measure of location measure of central tendency measure of variability

The interquartile range (IQR) encompasses what percent of the observations?

middle 50%

The median can also be described as the:

middle observation when the data values are arranged in ascending order

if the data has more than two modes, the data is

multimodel

ordinal

natural order

nominal

no natural order

quantitative

numerical data

a nonnumerical label or numerical code may be used for both

ordinal and nominal variables

two categories of categorical data

ordiual and

in stats, we are interested in obtaining info about total collection of observations, which we will refer to as

population

types of data

qualitative and quantitative

as a measure of variability, what is defined as the maximum value minus the minimum value?

range

measures of variability

range standard deviation variance

the population is often too large... thus, we try to learn about the population by observing and examining a sub group of its elements which is a

sample ($$$ + time)

what happens if the sample size (n) is odd

sample median is the single middle value

Student Major Exam Score Campus 1 Psych 92 yes 2. Business 75 no 3 Com 88 no 4 Econ 33 yes 5 Art 15 yes Who are the observations? who are the variables? How many subjects are there?

students are the observations major, exam score, campus are the variables there are 5 subjects

what does observations mean in data?

subjects or elements

numerical data

tells you how much or how many of something there is ( x )

variables

the characteristics of subjects about which we collect info can be divided into two categories

Interquartile Range (IQR)

the difference between the first and third quartiles

range

the difference between the highest and lowest scores in a distribution

what happens when a sample contains outliers

the median may be more representative of the sample than the mean is

what happens if the sample size (n) is even

the sample median is the average of the two middle values

A variable is classified as ordinal if:

there is a natural ordering of categories

what is the purpose of interpreting data?

to make conclusions

True or False: Abby has been keeping track of what she spends to stream movies. The last seven week's expenditures, in dollars, were 6, 4, 8, 9, 6, 12, and 4. The mean amount Abby spends on streaming movies is $7

true

True or False: The mean is a measure of central tendency

true

True or False: The value of the mean times the number of observations equals the sum of all of the data values

true

coding categories

two approaches; coding that matches your research purposes or generate codes from existing data

median

value in the middle when the data points are arranged in ascending order

population mean equation

µ (Greek mu) (= ∑x ÷ N) mean of all values in a POPULATION (sum of all DATA values divided by the number of DATA values in a POPULATION)