stats

Question 1

Continous variable

Answer 1

reflects a infinite number of potential values such as the average rainfall in a region

Question 2

Discrete variable

Answer 2

countable # of distinct values (heads or tails)

Question 3

to determine probability distribution

Answer 3

x values must be between 0 and 1 and sum of all must equal 1

Question 4

population

Answer 4

entire group

Question 5

sample

Answer 5

specific group you collect data from

Question 6

statistics

Answer 6

number describing a sample

Question 7

parameter

Answer 7

number describing the whole population

Question 8

accuracy

Answer 8

the mothod measures what it intended, the statistic correctly estimates the population parameter

Question 9

precise

Answer 9

if the method is repeated, the estimates are very consistent every statistic is nearly the same

Question 10

sampling methods that create bias

Answer 10

convience sampling
voluntary sampling

Question 11

preferred method

Answer 11

simple random sampling

Question 12

what are the properties of the sampling distribution

Answer 12

Sampling distribution’s mean (μ¯X) = Population mean (μ) Sampling distribution’s standard deviation (Standard error) = σ√n,
shape
central tendency
variabiliy

Question 13

example of measurement bias (leading question)

Answer 13

do you believe that obama’s horrible beliefs deserve another term in order to ruin our lives.

Question 14

example of measurement bias (confusing question)

Answer 14

do you not disagree with the not recent slight changes to the american culture?

Question 15

example of a nonresponse bias

Answer 15

do you currently have an std?

Question 16

example of voluntary response bias

Answer 16

an internet poll asks its visitors if they prefer cats or dogs

Question 17

example of a sample bias (nonrandom sample)

Answer 17

someone asks their twitter followers how they feel about the recent changes to congress

Question 18

how do you measure precision

Answer 18

by using standard error

Question 19

as population size increases, do accuracy and precision change?

Answer 19

no, both are unaffected

Question 20

as sample size increases, do accuracy and precision change?

Answer 20

accuracy in unaffected, and it becomes more precise.

Question 21

what does it mean to say that p-hat is a random variable

Answer 21

repeated sampling will result in different p-hat values.

Question 22

Suppose a statistician is interested in determining the percentage of Americans who prefer Burger King to McDonald’s. She surveys 100 randomly chosen Americans and finds that of those surveyed, 37% prefer Burger King.
Identify…
a. the population
b. the sample
c. the parameter
d. the statistic/estimator of the study

Answer 22

a. americans.
b. 100 americans.
c. proportion of americans who are burger king to the number of burger king fans.
d. 37%

Question 23

An analyst wants to know if there is a connection between time spent watching TV per day in hours and fat intake per day in grams. He performs a regression using time spend watching TV as the independent variable and fat intake as the dependent variable and finds that r = 0.5 and the regression line is given by: y = 45.8 + 10.3x
a). Explain what the correlation and regression line mean in the context of the data.
b). predict the fat intake of someone who watches 3 hours of tv a day
c). predict y when x=-2
d). which prediction is more reasonable?

Answer 23

a. The correlation means there is a moderate positive connection between time spent watching TV and fat intake.
The regression line means that for each additional hour of TV someone watches, we predict their fat intake will increase by 10.3 grams(slope), and the predicted fat intake of someone who watches no TV is 45.8(intercept)
b. 76.7
c. 25.2
d. b is more reasonable because you can’t watch a negative number of hours of tv in a day

Question 23

what are the 4 requirements of the central limit theorem

Answer 23

Random and independent sample, population at least 10x the sample size, np ≥ 10, n(1p) ≥ 10; if you don’t know p, use p-hat

Question 24

A pollster is trying to determine whether Candidate X will win an upcoming election(assume Candidate X needs 51% of the vote to win.) The pollster takes a random sample and determines that phat is .49 and the 90% percent confidence interval is given by (.45, .53). a. what is the margin of error? b. can the pollster be confident that candidate x will lose?

Answer 24

a. .04 or 4% b. no, the confidence interval is below 50% so we can't be sure.

Question 25

For each situation, state the appropriate null and alternative hypothesis... a. ohio claims that 23% of high school seniors are enrolled in at least 1 ap class. the principal wants to know if the proportion of seniors enrolled in ap class is higher. b. the cleveland metro police claim 8% of cleveland residents were the victims of a robbery or attempted robbery last year. a statistition believe that this number is too high.

Answer 25

a) H0: p = 0.23 vs Ha: p > 0.23 b) H0: p = 0.08 vs Ha: p < 0.08

Question 26

What should be done to create a confidence interval for a population proportion?

Answer 26

Add and subtract the margin of error to/from the sample proportion

Question 27

Which of the following does the confidence level measure?

Answer 27

The success rate of the method of finding confidence intervals

Question 28

Which of the following conditions regarding sample size must be met to apply the Central Limit Theorem for Samples?

Answer 28

The sample size is large enough that the sample expects 10 successes and 10 failures

Question 29

When taking samples from a population and computing the proportions of each sample, which of the following is always the same?

Answer 29

The population proportion

Question 30

What is the standard deviation of the sampling distribution called?

Answer 30

Standard error

Question 31

A researcher has designed a survey in which the questions asked do not produce a true answer. What is this an example of?

Answer 31

Measurement Bias

Question 32

In a confidence interval, what does the margin of error provide?

Answer 32

How far the estimate is from the population value

Question 33

Which of the following statements are false? I) The precision of an estimator does not depend on the size of the population II) The precision of an estimator does not depend on the size of the sample III) Surveys based on larger sample sizes have larger standard errors

Answer 33

Both II and III are false

Question 34

When applying the central limit therom for sample proportions, which of the following can be substituted for p when calculating the standard error if the value of p is unknown?

Answer 34

The value of the sample proportion

Question 35

If the conditions of a survey sample satisfy those required by the Central Limit​ Theorem, then there is a​ 95% probability that a sample proportion will fall within how many standard errors of the population​ proportion?

Answer 35

2 standard errors

Question 36

The null hypothesis is always a statement about what?

Answer 36

population parameter

Question 37

In hypothesis testing, the null hypothesis is best described by which of the following statements?

Answer 37

The null hypothesis always gets the benefit of the doubt and is assumed to be true throughout the hypothesis testing procedure

Question 38

What is true in a hypothesis test, the farther the test statistic is from 0?

Answer 38

The more null hypothesis is discredited

Question 39

In hypothesis testing, what does an extreme value for the test statistic indicate?

Answer 39

The null hypothesis is not true

Question 40

In hypothesis testing, when should the null hypothesis be rejected?

Answer 40

When the p-value is less than the significance value

Question 41

what do we assume about CLT

Answer 41

random smapling

Question 42

clt conditions to create a valid confidence interval

Answer 42

1. sample must be random and independent 2. normally distrubuted or equal to 30% 3. not more than 10% of population