STATS EXAM 1

p-value

to look at the statistical significance for correlation, check the _________

false (could be an identifier, etc.)

(t/f) a variable that consists of numbers is always quantitative variable

true

(t/f) outliers can make a weak correlation strong

false

(t/f): A p-value for correlation which is statistically significant implies the correlation is due to random chance

false

(t/f): If the correlation coefficient (r) of two variables is close to 0, this implies there is no relationship between these two variables?

false (we do not visualize identifiers)

(t/f): a bar chart is a good way to visualize an identifier variable

true

(t/f): a strong relationship can have correlation equal to 0

false

(t/f): an ordinal number is a quantitative variable that has been sorted in ascending or descending order

false

(t/f): outliers can dramatically impact the IQR and median

true

(t/f): quantitative variables must be numerical

false

(t/f): the correlation coefficient (r) is not affected by outliers

true

(t/f): there is sometimes a good reason to remove outliers

linear; non-linear

Correlation Coefficient is a measure of ________ association between two variables. Two variables could have a significant ____________ relationship.

N(98.2,0.7) number for percent higher than 99.26 area for 97.14 and 99.26 is 0.13 0.13/2 = 0.065 percent higher than 99.26 = 6.5%

In a 1992 article in the Journal of the American Medical Association, researchers reported that a more accurate average body temperature for adults is 98.2°F with a standard deviation of 0.7°F. Assume that a Normal model is appropriate N(98.2, 0.7). The area outside (shaded) of 97.14°F and 99.26°F is 0.13. What percent of adults have body temperatures higher than 99.26°F?

N(98.2,0.7) 80th percentile means 80% below OR say 20% above (top 20) --> begins at 0.842 (point for 60%) so 0.842 is the number we are looking for 80th percentile: (X - 98.2) / 0.7 = 0.842 X - 98.2 = 0.5894 X = 0.5894 + 98.2 X = 98.789 98.79 adult body temperature at the 80th percentile

In a 1992 article in the Journal of the American Medical Association, researchers reported that a more accurate average body temperature for adults is 98.2°F with a standard deviation of 0.7°F. Assume that a Normal model is appropriate N(98.2, 0.7). The middle 60% of N(0,1) is between -0.842 and 0.842 What adult body temperature is at the 80th percentile? (round to one decimal point)

SAMPLES give you STATISTICS to help you understand PARAMETERS about POPULATION

SSPP

N(470,24.4) your amount: 442 (442 - 470) / 24.4 -28/24.4 = -1.147 z-score: -1.15

The Chocolataboom Candy Company manufactures many types of different candies. Their most popular Valentine's Day box of candy follows a Normal Distribution with a mean of 470 grams and a standard deviation of 24.4 grams. You decide to buy a box of candy and weight it. Your box of candy weighs 442. Calculate the z-score for your box of candy.

identifier

UTK uses your student ID to track your database. this is a ______ type of identifier

absolute value

__________ tells strength of correlation

z-score of -1 is 70(1 standard deviation below the mean). (75-5= 70) -1 to 1 is 68% outside 1 is 16 68 + 16 = 84 OR 50 + 34 = 84 OR 100 - 16 = 84 84% is above 70 (or -1)

a STATS 201 test is normally distributed with a mean of 75 and a standard deviation of 5. what percent make above 70?

nominal categorical variable

a categorical variable in which the categories do not have a natural order

ordinal categorical variable

a categorical variable in which the categories have a natural order (category order)

scatterplots

all timeplots are ____

IQR

best measure of spread for skewed right distribution

nominal or ordinal

categorical variables are either called ______ or _______

mean

center for normal data

median

center for skewed data

sample

collected/used to make inferences about a population

2 quantitative variables straight enough no outliers

correlation conditions:

x and y

correlation measures linear strength between ________

linear relationship

correlation of 0 means there is still a relationship between variables but no ____________ _________

perfect linear

correlation of 1

shape center spread

describe the overall pattern of the distribution of a quantitative variable (univariate)

scatterplots and timeplots

display bivariate quantitative data

pie chart and bar chart (interchangeable)

graphic can be used for univariate categorical variables

quantitative

histogram variable type

the distribution follows the line

how does a normal probability plot determine if a distribution is normal?

unique

identifiers must be

bigger

if the data is right skewed to the median, the MEAN is ________

not due to pure chance

if this p-value falls below 0.05, we conclude that the linear relationship we are seeing is:

discrete

number has to be whole numbers

correlation

outliers can do anything when it comes to ______

true

outliers can make a strong correlation weak. outliers can also make the slope of a negative line positive

median and IQR

outliers do not impact _______

not significant (not correlation)

p-value greater than (<) 0.05

significant (correlation)

p-value less than (>) 0.05

categorical

pareto chart variable type

categorical

pie chart variable type

identifiers

special type of categorical variable

standard deviation

spread for normal data

IQR

spread for skewed data

quantitative

stem and leaf variable type

population

the group of individuals or things we want to understand

direction form strength unusual features

ways to describe bivariate quantitative data: (4 things)

0

weakest correlation strength

mosaic plots and contingency tables

what graphics can be used for bivariate categorical variables?

the plot doesn't thicken

what is NOT a condition for calculating correlation

mean

what is more impacted by skew? (mean or median)

how much

what phrase helps identify quantitative variables?