stats quiz 4

mathematically, probability is defined as

..... the number of ways an outcome may occur divided by the total number of possible outcomes

in a box, there are 8 red, 7 blue, and 6 green balls. one ball is picked up randomly. what is the probability that it is neither green nor red?

1/3 (7/21=1/3)

if a skew is more than__________ or less than __________, the skew is substantial

2 and -2

validity is concerned with

accuracy

researchers administer an IQ test to a group of high school students. then then correlate the scores on the IQ test with the students current high school gpa. this is an example of what type of validity?

concurrent validity

reliability is concerned with

consistency

"satisfaction" with a service may include a number of dimensions. if all of the dimensions are captured in a measurement tool/ survey/ questionnaire then the too is said to have _____

construct validity

a committee of experts is convened to review all of the items on a biostatistics final exam. if the committee feels that the test is representing all areas of knowledge the test is said to have _______

content validity

when a researcher is limited by time or money they may choose this sampling method

convenience sample

researchers want to determine the percentage of students who own iphones and android cell phones. they go to a popular spot on campus and ask first 100 students who pass what type of cell phone they own. what type of sampling method is this?

convienience

in developing a new test/measure we can correlate the score to an already established valid measure. if the tests are highly correlated we say the new test has _______

criterion validity

what type of validity is concerned with monitoring estimates of present performance and predictions of future performance

criterion validity

which of the following is concerned with monitoring estimates of present performance and prediction of future performance?

criterion validity

true or false: reliability refers to whether we are truly measuring what we are trying to measure

false

what is an example of independent probability?

flipping heads on a coin

a questionnaire/tool with 10 items gathers data about drug and alcohol use. if one of the items/questions in the questionnaire does not ask about drug/alcohol use then there is a lack of ______ in this tool

internal consistency reliability

2 graders watch a student-led presentation and score it using a rubric. if the percent agreement is high between the graders we say the test has

interrater reliability

________ is a measure of how peaked or flat the distribution is

kurtosis

the CDC is interested in evaluating the use of an evidence based teen pregnancy prevention program in counties across the US. they have a list of 2000 counties across all 50 states that have implemented the program of interest. how should they sample?

multistage cluster sample

if the mean of a set of scores is equal to the median, what can be said about the distribution?

no skew

if a distribution has a flat peak it is _______

platykurtic

if a distribution has a flat peak it is ________

platykurtic

if the distribution is peaked it has a _______ kurtosis

positive

when a distribution has a tail to the right of the distribution peak it is said to be _______ skewed

positively

if the mean of a set of scores is greater than the median , what can be said about the distribution?

positively skewed

highschool class rank is highly correlated with college GPA. this is an example of what type of validity?

predictive validity

highschool ranks is correlated with college gpa. this is an example of what type of validity?

predictive validity

a researcher is interested in the use of complementary medicine by residents of phoenix across various ethnic, gender, and class categories. which sampling method would be the best choice?

stratified random sample

a neighborhood with 1000 houses organized on a grid with 10 houses per block. if the houses on the NE corner of each bock are sampled (for a total of 100 households)- what sort of sample is this?

systematic

ASU wants to measure the success of the class of 2017. A list of all 2017 graduates is generated and every 20th graduate is contacted. what type of sample is this?

systematic random sample

a brief questionnaire/ test is used by primary care practitioners to assess whether patients are at risk of violence in the home. this questionnaire is used every time the patient is seen. if the results from the test are inconsistent overtime this test has

test-retest reliability

what is established when one test is given on multiple occasions and the results are consistent

test-retest reliability

which of the following are true about the sampling frame: sampling frame = a summary of the sample that is drawn form the population the registrar at ASU could provide a sampling frame of the population of current ASU students sampling frame = enumerated list of population it is the group from which the sample is drawn

the registrar at ASU could provide a sampling frame of the population of the current ASU students

what is true about convenience sampling

they are biased and nonrepresentative of the population they are cheaper and more time efficient than other sampling methods

true or false, if the probability of an event happening is 25%, then the probability of it not happening is 75%

true

samples should be _____________ and __________ when considering the population from which they were drawn.

unbiased and representative