Introductory Statistics-Chapter 7

inferences/inferences

The size of the sample determines the accuracy of any​ _____________, it does not determine if the ___________ are valid. (MYSTATLAB)

Central Limit Theorem

To apply the ________________ for Sample​ Proportions, the products of the sample size times the sample proportion and the sample size times ​(1minussample ​proportion) must both be greater than or equal to 10.

nonresponse bias

When people fail to answer a question or respond to a survey it is called ___________________. The people who do not respond might have different opinions than those who do respond. This lack of participation from parts of the population could result in a biased survey. (MYSTATLAB)

bias

___________ is measured as the distance between the mean value of the estimator (the center of the sampling distribution) and the population parameter. (318)

bias/bias/bias

____________ indicates the typical outcome of surveys repeated again and again. If the ______ is 0, we will typically get the right value. If the _________ is 0.10, then our estimate will characteristically be 10 percentage points too high. (322)

Measurement bias

________________ occurs when the method of data collection does not produce valid results.

surveys

_________________ are probably the most often encountered application of statistics. (308)

precision

_________________ is reflected in the spread of the sampling distribution and is measured by using the standard deviation of the sampling distribution.

probability

_________________ tells us how often an event happens if we repeat an experiment in an infinite number of times. (322)

confidence intervals

___________________ are often reported as the estimate plus or minus some amount. (329)

statistical inference/statistical inference

__________________________ is the art and science of drawing conclusions about a population send the basis of observing only a small subset of that population. _____________________ always involves uncertainty, so an important component of the science is measuring our uncertainty. (309)

statistics/statistic/parameter

an important difference between statistics and parameters is that ______________ are knowable. Anytime we collect data, we can find the value of a _________________. in example 1, we know that 25% of those surveyed felt that their partner was distracted by the cell phone. In contrast, a ______________ is typically unknown. We do not know for certain the percentage of all people who felt this way about their partners. The only way to find out would be to ask everyone, and we have neither the time nor the money to do this. (309)

response bias

because of _______________, you should always question what type of people were included in the survey. But the other side of this point is that you should also question what people were left out. (311)

sampling bias/measurement bias/naturally biased

bias can enter a survey in three ways. The first is through ________________________, which results from taking a sample that is not representative of the population. A second way is __________________, which comes from asking questions that do not produce a true answer. For example, if we asked people their income, they are likely to inflate the value. In this case, we get a positive (or upward) bias: our estimate will tend to be too high. This kind of bias occurs when measurements tend to record values larger or smaller than the true value. The third way occurs because some statistics are __________________. (310)

random sample

how do we collect a sample that has as little bias as possible in as representative of the population? Only one way that works: to take a ______________________. (312)

census/census/census

if the population is relatively small, we can find the exact value of the parameter by conducting a _____________. A _______________ is a survey in which every member of the population is measured. For example, if you wish to know the percentage of people in your classroom or left-handed, you can perform a _______________. The classroom is the population, and the parameter is the percentage of left-handers. (308)

simple random sampling (SRS)

in theory, we can take a _____________________ by assigning a number to each and every member of the population. We then use a random number table or other random number generator to select our sample, ignoring numbers that appear twice. (312)

random

it can't be emphasized enough that if our sample is not _____________, there's really nothing we can learn about the population. We can't measure a survey's precision, and we can't know how large or small the bias might be. (312)

method

statisticians evaluate the _______________ used for a survey, not the outcome of a single survey. (314)

estimators/estimates/estimator/

statistics are sometimes called _________________, in the numbers that result are called ________________. for example, our __________________ is the proportion of people in a sample who say they will vote in the next election. When we conduct the survey, we find, perhaps, that 0.75 of the sample say they will vote. This number, 0.75, is our estimate. (309)

standard error

surveys based on larger sample sizes have smaller ___________________ and therefore better precision. Increasing the sample size improves precision. (321)

Bias

the accuracy of our estimation method is measured in terms of the __________. (315)

standard error

the precision of our estimation method is measured by a number called the __________________. (315)

sampling distribution

the probability distribution of the sample proportion has a special name: __________________. this term reminds us that the sample proportion is not just any random outcome; it is a statistic we use to estimate a population parameter. (317)

standard error/standard error

the standard deviation of a sampling distribution has a special name: the _________________. The _________________ measures how much our estimator typically varies from sample to sample. (318)

Central Limit Theorem (CLT)

this theorem gives us a very good approximation of the sampling distribution without our needing to do simulations. (323)

response bias

today, the most commonly encountered biased surveys are probably Internet polls. Internet polls suffer from what is sometimes called ____________________. people tend to respond to such surveys only if they have strong feelings about the results; otherwise, why bother? This implies that the sample of respondents is not necessarily representative of the population. (311)

biased/biased

unfortunately, it is far easier to conduct a bad survey than to conduct a good survey. One of the many ways in which we can reach a wrong conclusion is to use a survey method that is _________________. a method is ____________________ if it has a tendency to produce an untrue value. (310)

Inference

whenever we draw a conclusion about a large group based on observations of some parts of that group, we are making a ________________. (307)

statistic

A _____________ is a measurable estimator of an often unknown population parameter. (MYSTATLAB)

parameter/statistic

A ______________ is a measure of the​ population, such as the average height of everyone in a​ school, and a _____________ is a measure of a​ sample, such as the average height of 5 people randomly selected in the same school. (MYSTATLAB)

parameter

A ______________ is a numerical value that characterizes some aspect of the population. (MYSTATLAB)

population

A _______________ is a group of objects or people we wish to study. Usually, this group is large - say, the group of all US citizens, or all US citizens between the ages of 13 and 18, or all senior citizens. However, it might be smaller, such as all phone calls made on your cell phone in January. (308)

Population

A ________________ is a group of objects or people to be studied. (MYSTATLAB)

Statistic

A ________________ is sometimes called an estimator. A statistic is a numerical characteristic of a sample. (MYSTATLAB)

confidence interval

A _________________ provides two pieces of information: (1) a range of plausible values for a population parameter, and (2) a confidence level, which expresses our level of confidence in this interval. (330)

parameter

A ___________________ is a numerical value that characterizes some aspect of a population. For example, political pollsters want to know what percentage of people say they will vote in the next election. Drunk driving opponents want to know what percentage of all teenagers with drivers licenses have drunk alcohol while driving. (308)

random sample

A _______________________ does not mean that we stand on a street corner and stop whomever we like to ask them to participate in our survey. (Statisticians call this a convenience sample, for obvious reasons). A _______________________ must be taken in such a way that every person our population is equally likely to be chosen. (312)

95%

The probability that a sample proportion will fall within 2 standard errors of the population proportion is​ ______.

survey

The quality of the ____________ depends on the method used of the survey.

standard error

The standard deviation of the sampling distribution is called the ________________.

Central Limit Theorem

To apply the _____________ for Sample Proportions the sample size must be large enough that the sample expects at least 10 successes and 10 failures.

Central Limit Theorem

To apply the ________________ for Sample Proportions when the sample is collected without​ replacement, the population size must be at least 10 times bigger than the sample size.

simple random sampling (SRS)

In ___________________________, we draw subjects from the population at random and without replacement. Without replacement means that once the subject is selected for a sample, that subject cannot be selected again. This is like dealing cards from a deck. Once a card is Dell for a hand, no one else can get the same card. a result of this method is that every sample of the same fixed size is equally likely to be chosen. As a result, we can produce unbiased estimations of the population parameters of interest and can measure the precision of our estimator. (312)

nonreponse​ bias/voluntary response​ bias

It is important to know whether there is _______________, which can be judged based on what percentage of people who were asked to participate actually did​ so, or _______________, which can be judged by whether the researchers chose people to participate in the survey or people themselves chose to participate.​ .

bias

The _________ of a sampling distribution is measured by computing the distance between the center of the sampling distribution and the population parameter.

central limit theorem (CLT)

The ______________ has several versions. The one that applies to estimating proportions in a population tells us that if some basic conditions are met, then the sampling distribution of the sample proportions close to the normal distribution. Condition one: random and independent. Condition to: large sample. Condition three: big population. (323)

precision

The ______________ of an estimator does in fact depend on the size of the​ sample, and surveys based on larger sample sizes actually have smaller standard errors.

precision

The ________________ of an estimator does not depend on the size of the population; it depends only on the sample size. An estimator based on a sample size of 10 is just as precise in a population of the thousand people as in a population of 1 million. (320)

confidence level

The __________________ measures the capture rate for our method of finding confidence intervals. (330)

margin of error

The __________________ tells how far from the population value our estimate can be. (330)

confidence level/confidence level/confidence level

The __________________ tells us how often the estimation method is successful. Our method is to take a random sample and calculate a confidence interval to estimate the population proportion. If the method has 100% _____________________, that method always works. If the method has a 10% _________________, it works in 10% of the surveys. (330)

Central Limit Theorem (CLT)

The ___________________ for proportions requires (1) a random sample with independent observations; (2) ; a large sample; and (3) if SRS is used, a population with at least 10 times as many members as are in the sample. (325)

Sample

most populations we find interesting or too large for a census. For this reason, we instead observe a smaller sample. A _______________ is a collection of people or objects taken from the population of interest. (308)

sample proportion

no matter how many different samples we take, the population proportion is always the same, but the _______________ can be different because its value changes from sample to sample. (317)

statistic/statistic/statistic

once a sample is collected, we measure the characteristic were interested in. A __________________ is a numerical characteristic of a sample of data. We use _____________________ to estimate parameters. For instance, we might be interested in knowing what proportion of all registered voters will vote in the next national election. The proportion of all registered voters will vote in the next election is our parameter. Our method to estimate this parameter is to survey a small sample. The proportion of the sample who say they will vote in the next election is a _______________________. (308)

simple random sampling (SRS)

one basic method of developing a true random sample is called _____________________. (312)

nonresponse bias

random sampling does not cure all ills. ________________ can still be a problem, and the possibility always exists that methods of taking the random sample are flawed (as they are fully landline telephones are used when many in the population you cell phones). (313)