STATS 1&2
Why is a sample used more often than a population?
It is usually impossible to count the entire population
what are the two branches of statistics?
descriptive statistics and inferential statistics
true or false : data at the ordinal level are quantitative only
false, data at the ordinal level can be qualitative or quantitative
true or false: in a frequency distribution the class width is the distance between the lower and upper limits of a class
false, in a frequency distribution, the class width is the distance between the lower or upper limits of consecutive classes.
true or false: a statistic is a measure the describes a population characteristic
false: a statistic is a measure that describes a sample characteristic
after constructing a relative frequency distribution summarizing IQ scores of college students, what should be the sum of the relative frequencies ?
if percentage are used, the sum should be 100%. if proportions are used, the sum should be 1.
what is an inherent zero? examples that have inherent zeros?
inherent zero- a zero that implies "none" example- average age of college students in years, average month precipitation in inches, and maximum wind speed during a hurricane
the years that a television show on a particular network won an award for best comedy series as shown below: 1951,1962,1976,1986,1990. whats the level of measurement?
interval, because the data can be ordered and differences between entries are meaningful , but a zero entry is not an inherent zero
what is the level of measurement for the jersey numbers for soccer players?
nominal, because the data are categorized using numbers, but no mathematical computations can be made
parameter or statistic : a certain zoo found that 8% of its 843 animals were nocturnal
parameter, because the data set of all 843 animals in a zoo is a population
parameter or statistic: in a study of all 2594 employees at a college it is found that 35% own a vehicle
parameter, because the value is a numerical measurement describing a characteristic of a population
population or sample: the salary of each baseball player in a league
population, because it is a collection of salaries for all baseball players in the league
a survey of 12,056 women in a particular country found that 47.3% relieved an influenza vaccine for a recent flu season. identify the population and sample.
population- the immunization status of all women in the country sample- the immunization status of the 12,056 women selected
qualitative or quantitative: state of residence
qualitative, because the state of residence describes an attribute or characteristc
qualitative or quantitative: carrying capacities of flatbed trucks
quantitative, because carrying capacities are numerical measurements
population or sample: the diastolic blood pressure of 10 patients in a hospital containing 200 patients
sample, because the collection of 10 patients blood pressure is a subset of all the patients in the hospital
how do you find range of a data set?
the range is found by subtracting the minimum of data entry from the maximum data entry
relationship between variance and standard deviation
the standard deviation is the positive square root of the variance. the standard deviation and variance can never be negative. squared deviations can never be negative.
true or false: it is impossible for the census bureau to obtain all the census data about the population of the united states
the statement is true
why is standard deviation used more frequently than the variance
the units of variance are squared. its units are meaningless
true or false: class boundaries ensure that consecutive bars of a histogram touch
true
given a data set, how do you know when to measure Standard deviation or variance?
when given a data set, one would have to determine if it represented the population or if it was a sample taken from the population. If the data are a population, the standard deviation is calculated. if the data are a sample, then variance is calculated.
what is the difference between a parameter and a statistic?
-a parameter is a numerical description of a population -a statistic is a numerical description of a sample characteristic
which levels of measurements can be qualitative?
1.) ordinal 2.) Nominal
How is a sample related to a population?
A sample is a subset of a population.
true or false: a population is the collection of some outcomes, responses, measurements, or counts that are of interest
false: a population is the collection of all outcomes, responses, measurements, or counts that are of interest.
class boundaries?
class boundaries, are the numbers that separate classes without forming gaps between them for integer data, the corresponding class limits and class boundaries differ by .5
class limits?
class limits are the least and greatest numbers that can belong to the class.
find class width, lower class limits, and the upper class limits: min-9 max-78 class-6
class width- 12 (78-9/6 = 11.5--ROUND) LCL- 9,21,33,45,57,69 UCL- 20,32,44,56,68,80