Intro Stats - Module 3 Quizzes

Suppose the sample size is n = 100 and the proportion of interest in the population is 25%. What is the Standard Error?

0.0433

In which way(s) can bias (a tendency to produce an untrue value) enter a survey? A. From taking a sample that is not representative of the population B. From asking questions that do not produce a true answer C. From statistics that are naturally biased D. All of the above

D. All of the above

We use the InverseNormal function when we want to find A. A measurement, given the probability B. A measurement, given the percentile C. A measurement, given the left area under the normal curve D. All of the above

D. All of the above

Which of the following condition(s) on the sample must be met for applying the Central Limit Theorem for estimating proportions in a population? A. Random and independent B. Large sample C. Big population D. All of the above

D. All of the above

When you are finding probabilities with normal models, the most helpful step is to A. sketch the curve to represent the normal model B. shade in the region of interest C. label the curve appropriately D. all of the above, in that order

D. all of the above, in that order

The probability distribution of discrete outcomes can be displayed A. as a graph B. as a table C. as a density curve D. both A and B E. both A and C F. both B and C

D. both A and B

Determine if the following variable represents a continuous or discrete random variable. "The numbers of songs on an mp3 player"

Discrete Random Variable

The standard normal model is an important concept because it allows us to find the probabilities of any normal model using

The z-score

TRUE OR FALSE. A confidence interval provides a range of plausible values for a population parameter.

True

TRUE OR FALSE. A sample is a collection of people or objects taken from the population of interest.

True

TRUE OR FALSE. Bias is measured using the center of the sampling distribution. It is the distance between the center and the population value.

True

TRUE OR FALSE. If the conditions of a survey sample satisfy those required by the Central Limit Theorem, then the probability that a sample proportion will fall within one standard error of the population value is about 68%.

True

TRUE OR FALSE. It is correct to say that the process that produces intervals captures the true population parameter 95% of the time.

True

TRUE OR FALSE. Statistical inference is the art and science of drawing conclusions about a population on the basis of observing only a small subset of that population.

True

TRUE OR FALSE. Statisticians have developed notation for keeping track of parameters and statistics. In general, Greek characters are used to represent population parameters. Statistics (estimates based on a sample) are represented by English letters.

True

TRUE OR FALSE. The confidence level measures the capture rate for our method of finding confidence intervals.

True

TRUE or FALSE. If you don't know the value of p, then you can substitute the value of p-hat to calculate the expected number of success and failures when checking that the sample size is large enough.

True

TRUE or FALSE. If you don't know the value of p, then you can substitute the value of p-hat to calculate the standard error.

True

True or False: A characteristic of a binomial model is that the number of trials is a fixed number.

True

True or False: Discrete outcomes (or discrete variables) are numerical values that you can list or count.

True

True or False: The binomial probability model is useful in many situations with discrete-valued numerical variables (typically counts, whole numbers).

True

In the Normal curve, if the standard deviation is large, then the normal curve is

Wide and low

A numerical value that characterizes some aspect of a population is called a

Parameter

The probability distribution of p-hat has a special name:

Sampling distribution

A numerical characteristic of a sample of data is called a

Statistic

To convert a value to its z-score, take the data value and

Subtract the mean, then divide by the standard deviation

The condition that the population must be "big" is satisfied if the population is

Ten times the sample size

To obtain a 95% confidence level, we use a margin of error of

1.96 standard errors

How can we tell if the sample size is big enough before applying the Central Limit Theorem? (Let n be the sample size and let p-hat be the proportion of the sample having the desired characteristic.) CHOOSE ALL THAT APPLY. A. n(p-hat) has to be less than or = to 10. B. n(p-hat) has to be greater than or = 10 AND n(1 - p-hat) has to be greater than or = to 10. C. There has to be at least 10 success and 10 failures. D. The sample size has to be at least 50. E. The sample size has to be at least 100.

B. n(p-hat) has to be greater than or = 10 AND n(1 - p-hat) has to be greater than or = to 10. C. There has to be at least 10 success and 10 failures.

A probability distribution, sometimes called a probability distribution function, tells us A. the probability of each outcome B. all the possible outcomes of a random experiment C. Both A and B D. none of the above

C. Both A and B

Which of the following is NOT a condition of the binomial distribution? A. There are two possible outcomes. B. There are a set number of trials, n. C. The trials are dependent. D. The probability of success is constant from trial to trial.

C. The trials are dependent

TRUE OR FALSE. An important difference between parameters and statistics is that parameters are knowable.

False

TRUE OR FALSE. In most situations in the "real world," we know the value of the population proportion.

False

TRUE OR FALSE. It is correct to say that a particular confidence interval has a 95% (or any other percent) chance of including the true population parameter.

False

TRUE OR FALSE. No matter how many different samples we take, the value of p (the population proportion) changes from sample to sample, but the value of p-hat is always the same.

False

TRUE OR FALSE. We use parameters to estimate statistics.

False

True or False: The standard Normal model has a mean of 1 and a standard deviation of 0.

False

The confidence level measures

How often the estimation method is successful

A confidence interval is often reported as an estimate plus or minus some amount. This "some amount" is called

Margin of error

In the Normal curve, if the standard deviation is small, then the normal curve is

Narrow and tall

If a sample size is n = 100 and p-hat = 9%, is the sample size large enough to apply the Central Limit Theorem for Sample Proportions?

No

In the 1960 presidential election, 34,226,731 people voted for Kennedy; 34,108,157 for Nixon, and 197,029 for third-party candidates. Would it be appropriate to find a confidence interval for the proportion of voters choosing Kennedy?

No. We already know the population proportion. We only need a confidence interval when we have a sample proportion and want to generalize about the population.

Many numerical variables, in which researchers have historically been interested, have distributions that what model provides a close fit?

Normal model