Task 2

Question 1

Statistics are also known as…

Answer 1

estimates

Question 2

What do density curves represent?

Answer 2

the probability of a continuous random variable

Question 3

Density curves are used on

Answer 3

histograms

Question 4

What is the area under a density curve?

Answer 4

1

Question 5

What kind of density curves are there?

Answer 5

normal, symmetric, skewed etc

Question 6

Where is the mode on a density curve?

Answer 6

the highest point

Question 7

How do you calculate the median on a density curve?

Answer 7

total area halved on each side

Question 8

How do you locate quartiles on a density curve?

Answer 8

divide the area into quartiles

Question 9

The larger the standard deviation, the larger the…

Answer 9

spread

Question 10

Percentages for normal distribution

Answer 10

68% 95% 99.7%

Question 11

Define standardizing

Answer 11

a linear transformation that transforms data into the standard scale of z-scores

Question 12

What does a z score tell us?

Answer 12

tells us how many standard deviations the original observations fall away from the mean and in which direction

Question 13

If observations are larger than the mean they are
a) positive
b) negative
when standardized

Answer 13

positive

Question 14

Does standardizing affect the distributional characteristics e.g. shape and cumulative density?

Answer 14

no

Question 15

What is the mean of the standard normal distribution?

Answer 15

0

Question 16

What is the standard deviation of the standard normal distribution?

Answer 16

1

Question 17

Define cumulative proportion

Answer 17

the proportion of observations a distribution that lie at or below a given value

Question 18

Does standardizing changes the slope and intercept of the line in our plot?

Answer 18

yes but the line does not turn

Question 19

How do we find the sampling distribution of the mean of x?

Answer 19

we take as many simple random samples of size 80 and calculate the mean for each sample

Question 20

What does the precision of an estimate depend on?

Answer 20

the spread of the sampling distribution

Question 21

What is the Central Limit Theorem?

Answer 21

draw a SRS of size n from any population with population mean and finite standard deviation

when n is large, the sampling distribution of the sample mean is approx normal

Question 22

Define exponential distribution

Answer 22

a process in which events occur continuously and independently at a constant average rate

Question 23

What does the mean and standard deviation equal in an exponential distribution?

Answer 23

1

Question 24

What is the formula to calculate the height under a density curve at a given point x?

Answer 24

see notes page 2

Question 25

Define unbiased estimate

Answer 25

applies to sample mean, expected value of sampling distribution of the statistic of interest = parameter of interest in the population i.e. μx̅ = μ

Question 26

Define efficiency

Answer 26

an estimator is more "efficient" than another if the spread is smaller

Question 27

Efficiency is in relation to a ____ and variability is in relation to a ____

Answer 27

statistic, variable

Question 28

Define standard error

Answer 28

a measure of the statistical accuracy of an estimate, equal to the standard deviation of the theoretical distribution of a large population of such estimates (related to sampling distribution)

Question 29

Define central limit theorm

Answer 29

in some situations, when independent random variables are added, their properly normalized sum tends toward a normal distribution even if the original variables themselves are not normally distributed.

Question 30

What kind of variables are estimates?

Answer 30

random variables

Question 31

A sample is an example of a ___ ____

Answer 31

elementary outcome

Question 32

What kind of distribution is a sampling distribution?

Answer 32

a theoretical distribution

Question 33

What makes an estimate unbiased?

Answer 33

if averaged across an infinite number of estimations it would yield the parameter again

Question 34

Why is the standard deviation of a sampling distribution also known as the standard errror?

Answer 34

Because its the average deviations a mean will deviate from the actual mean when various samples are drawn

Question 35

How can we minimise the standard error?

Answer 35

drawing a larger sample e.g. larger than 25

Question 36

How can we make x bar a more efficient estimator?

Answer 36

increase sample size as it reduces standard error therefore predicts the population much better

Question 37

What do disjoint events look like on a contingency table?

Answer 37

=0

Question 38

Are distribution and bias related?

Answer 38

no

Question 39

What do outliers do to the mean?

Answer 39

skew it

Question 40

Always draw with replacement unless ....

Answer 40

conditional

Question 41

What distribution represents population distribution better? a) sampling b) sample scores

Answer 41

b