statistics test 1

give an example of a qualitative variable.

name

give an example of a variable that we could observed that would fit with single value grouping

numbers of cars per person.

what is the difference between an observational study and a designed experiment?

observational: simply observe and take measurements. designed: impose treatments and controls and then observe and take measurements.

what is a census?

obtain info for the entire population.

a histogram displaying percents is called a _________.

percent histogram

what does a population distribution and a sample distribution provide?

population: all the values for the population in a table, chart, graph, or list. sample: a table, chart, graph, or list of data for the sample.

what is the difference between population mean and sample mean?

population: average for the entire population. denoted by mu. sample: average for the sample. denoted by x-bar.

define population and sample.

population: collection of all individuals or things under consideration. sample: the part of a population in which info is collected.

what is the difference between population data and sample data?

population: observations for ALL people or things in the population. sample: observations for THE people or thing in the sample.

a bar chart is for ________ data.

qualitative

histogram is for ______ data.

quantitative

a histogram displaying relative frequencies is called a -___________.

relative frequency histogram

explain the meaning of distribution of a variable.

the distribution of a variable is another name for the population distribution.

a designed experiment is described. identify the specified element of the experiment. in a clinical trial, 780 participants suffering from high blood pressure were randomly assigned to one of three groups. over a one-month period, the first group receive a low dosage of an experimental drug, the second group received a high dosage of the drug, and the third group received placebo. the diastolic blood pressure of each participant was measure at the beginning and at the end of the period and the change in blood pressure was recorded. identify the factor.

the dosage of the drug

determine whether the study depicts an observational study or an experiment. twenty patients with Parkinson's disease are divided into two groups. one group receives and experimental drug to fight palsy, the other a placebo. after one year, memory recall is measured.

the study is an experiment because the researchers control one variable to determine the effect on the response variable.

the total of the frequency column in a frequency table should equal_______.

to how many pieces of data there are

what is the difference in a treatment group and a control group?

treatment: specific treatment. control: placebo.

suppose that you have constructed a stem-and-leaf diagram and discover that it is only moderately useful because there are too few stems. how can you remedy the problem?

use five lines for each stem, with the first line for the leaf digits 0 and 1, the second line 2 and 3, the third line 4 and 5, the fourth line 6 and 7, and the fifth line 8 and 9. you can also use two lines for each stem, with the first line 0-4 and the second line 5-9.

give an example of a discrete, quantitative variable.

MUW ID number

explain why a sample of 1125 accountants from Atlanta taken to estimate the average income of all residents of Atlanta is not a representative sample.

a representative sample should reflect as closely as possible to the relevant characteristics of the population. in this example, the sample only considers accountants from Atlanta not the entire population.

what is a distribution for a data set?

a table, graph, or formula that provides the values of the observations and how often they occur. the general or overall shape of a distribution is a characteristic of interest for the data set.

what is the difference between descriptive and inferential statistics?

descriptive: method for organizing and summarizing info. inferential: method for drawing conclusions and measuring the reliability of the conclusion based on info from a sample of a population.

what are the different names for distribution shapes?

1. bell shaped 2. triangular 3. j shaped 4. reverse j shaped

statistics

1. data: how we gather it, organize it, and summarize it. 2. graphs.

discuss the Empirical rule.

1. for data with a BELL SHAPED DISTRIBUTION. 2. ROUGHLY 68% of data values lie within 1 standard deviation of the mean. 3. ROUGHLY 95% of the data values lie within 2 standard deviations of the mean. 4. ROUGHLY 99.7% of the data values lie within 3 standard deviations of the mean.

discuss Chebyshev's rule.

1. it is for ANY data set. 2. AT LEAST 75% of the data values fall within 2 standard deviations of the mean. 3. AT LEAST 89% of the data values fall within in 3 standard deviations of the mean.

list the steps for systematic random sampling.

1. m = pop size/sample size. 2. randomly select an integer k in the 1 to m range. 3. select population items k, k+m, k+2m....until the sample is the desired size.

determine whet the study depicts an observational study or a designed experiment. fifty children are divided into two groups. one group is exposed to a video on bullying. the other is not. after one week, both groups are questioned about their attitudes about violence.

designed

in testing a new drug for its effectiveness in treating ADD, which type of study would be most appropriate?

designed study

what is range?

difference between max and min values.

identify the following as qualitative, quantitative continuous, or quantitative discrete. a) a person's name. b) major c) gender d) GPA e) ACT score f) advisor g) ID number

1. qualitative 2. qualitative 3. qualitative 4. quantitative, continuous 5. quantitative, discrete 6. qualitative 7. quantitative, discrete

identify the following as qualitative, quantitative continuous, or quantitative discrete. 1. time 2. magnitude 3. depth 4. NST 5. region

1. quantitative continuous 2. quantitative continuous 3. quantitative continuous 4. quantitative discrete 5. qualitative

name the different methods to obtain a simple random sample.

1. tickets in a box/hat. 2. random number table; 01, 02, 03, ..., 87 3. within software such as Excel of StatCrunch. 4. TI-83: MATH>PRB?randInt

list the important things to include with graphs and charts.

1. title 2. all axes need labels 3. scales need to be uniform. 4. indicate a break when appropriate

cluster sampling.

divide population into clusters; randomly select clusters, use all items in the chosen clusters to form the sample.

stratified sampling.

divide population into subpopulations; from a subpopulation, obtain a simple random sample that is proportional to the size of the subpopulation; combine samples from the subpopulations as the overall sample.

simple random sampling.

each possible samples of a given size is equally likely to be obtained.

a histogram displaying frequencies is called a __________.

frequency histogram

what is the difference between frequency and relative frequency?

frequency is the number of times a particular distant value occurs. relative frequency is the ration of the frequency of a value to the total number of observations.

give an example of a continuous, quantitative variable.

high school GPA

the total of the relative frequency column in a frequency table should equal __________.

1 or very close to 1.

what is a truncated graph?

a graph where part of the one of the axes has been cut off or truncated.

what is the difference between percentage and relative frequency?

a relative frequency is that same as percentage expressed as a decimal.

what is a distribution?

a representation of collection of data, perhaps in a table, a list, or a graph.

identify the following as either descriptive or inferential. a) the average credit hours for students in this room is 14.7. b) the average credit hours for MUW students is 14.7 based on the students in this class. c) a CNN poll indicates that 61% of Americans favor candidate X. d) of the people polled, 61% favor candidate X.

a) descriptive b) inferential c) inferential d) descriptive

identify each situation as being an observational study or a designed experiment. a) a study of how exercise affects sleep time is planned. b) a report on the semester grades of new transfer students in the Spring 2016 semester.

a) designed b) observational

answer true or false for the following and explain. a) two data sets that have identical frequency distributions have identical relative frequency distributions. b) two data sets that have identical relative frequency distributions have identical frequency distributions. c) use your answers to parts a and b to explain why relative-frequency distributions are better than frequency distributions for comparing two data sets.

a) true. if we are given the same values for frequency, they must add up to the same total number pieces of data. we know to get the relative frequency we divide the frequency by the total number of pieces of data. since this is the case, the relative frequency will be the same. b) false. we divid the frequency distribution by the total number pieces of data and that gives the relative frequency value. say the value is .25. there can be more than one set of values that gives us this answer. c) relative frequency distributions look at the data as a whole. we know we divide the frequency distribution by the total number pieces of data to get the relative frequency, but the frequency distribution does not look at the total pieces of data.

in an experiment investigating weight loss in connection with exercise and sleep, individuals are assigned randomly to groups who will engage in running, walking, swimming, tennis, or no exercise and will also have their sleep amount controlled to be less than 6 hours, 6-8 hours, or more than 8 hours. a) what is the response variable? b) give the factor(s) in this experiment. c) give an example of a treatment in this experiment. d) how many different treatments are possible in this scenario?

a) weight loss b) exercise (running, walking, swimming, tennis, or no exercise) and amount of sleep c) swimming and 6-8 hours of sleep d) 15 different combinations

an education research randomly selects 38 schools from one school district and interviews all the teachers at each of the 38 schools. identify the type of sampling used in this sample.

cluster sampling

what is the difference between completely randomized design and randomized block design?

completely randomized: all subjects are assigned randomly among the treatments. randomized block: subjects are assigned randomly among all the treatments separately within each block.

for a collection of data representing the weights of various objects, what type of grouping would be best to use?

cut point. weight=continuous

presented below is a "data scenario." decide which type of grouping is probably the best. the rule tank capacity of all new SUV models, to the nearest tenth of a gallon.

cutpoint grouping

what is sampling?

how we gather data

standard deviation ________ resistant.

is

the median _______ resistant.

is

the mean _______ resistant.

is not

what is a frequency distribution of quantitative data and why is it useful?

it is a listing of the distinct values and their frequencies. it is useful because it provides a table of the values of the observations and how often they occur.

give a legitimate motive for truncating the axis of a graph.

it may allow relevant information to bey conveyed easier.

what type of grouping would be best for the number of pairs of shoes in a person's closet?

limit grouping

define mean, median, and mode.

mean (average): is calculated by adding all the data values and dividing by how many data values there are. median: middle data value when data is listed in order. median is at position= n+1/2 in the ordered list. if n is odd, the median is the middle data value. if n is even, the median is the average of the 2 middle values. mode: data values with the hight frequency.

a sample distribution is the distribution of _____________.

sample data

explain the meaning of sample data.

sample data are the values of a variable for a sample of the population.

representative sample.

should reflect as closely as possible to the relevant characteristics of the population.

what is the difference between single value grouping, limit grouping, and outpoint grouping?

single value: just one data value corresponds to each group; useful when only a few distinct values are possible. limit: this is for discrete data. cut point: this is for continuous data. the following is for limit and cut point: there is a lower and upper limit of each class. all classes should have the same width. no overlap of classes. should use between 5 and 20 classes.

for the data on the size of household, what type of grouping would be best to use, and why?

single-vlaue

if you have a legitimate motive for truncating the graph, how can you correctly obtain that objective without creating the possibility of misinterpretation.

start the axis at 0 and includes a special symbol, such as slashes, to indicate that part of the axis is missing.

discuss the relative advantages and disadvantages of stem-and-leaf diagrams versus frequency histograms.

stem-and-leaf diagrams are easier to make and contain more information than frequency histograms. however, they are not ver useful for large data sets.