IDS 270 Practice Exam 2024 Questions & Answers 100% Correct Verified

a telephone survey research company is not able to get a woman to answer questions about local traffic conditions because she is busy baking cookies - nonresponse bias a student polls his friends to get data regarding grades at his university and represents his findings as being representative of all students at that university - convient sample a certain IDS 270 instructor does not answer questions about his drinking habits while an undergraduate at the University of Michigan with complete accuracy - response bias Nightline posts results from a call in poll indicating that 60%of callers are in favor of gun control - volentary response bias a researcher wants to estimate costs of higher education. He first puts the entire set of colleges into groups that are relatively similar: Private colleges, 4 year universities, community colleges, etc. He then samples from each of these groups and gets the cost of attending the college from the sample. - stratified sampling mean of 2, 4, 6, 8 - 20/4=5 median of 2, 4, 6, 8 - add the two middle numbers and divide by two. 10/2=5 standard deviation of 2, 4, 6, 8 - (2-5)^2+(4-5)^2+(6-5)^2+(8-5)^2=20 20/3 (3 bc n-1) square root of 20/3 Observational study - observes individuals and measures variables of interest but does not attempt to influence the responsesexperiment - deliberately imposes some treatment on individuals to observe their responses confounding - two variables (explanatory variables of lurking variables) are counfouded when their effects on a response variable cannot be distinguished from each other sample - we can't afford to ask all the adults so we put the question to a _____ chosen to represent the entire adult population. type of observational study simple random sample - the size n consists of n individuals from the population chosen in such a way that every set of n individuals has an equal chance to be in the sample actually selected probability sample - a sample chosen by chance. we must know what samples are possible and what chance or probability each possible sample has. stratified random sample - first divide the population into groups of similar individuals , called strata. then choose serrate SRS in each stratum an combine these SRSs to form the full sample. Current population survey - conducts interviews in about 55,000 households each month. multistage sample - It would be too expensive and not practical to maintain a list of all U.S. households from which to select an SRS. the current population survey therefore uses a ____________ wording effects - the wording of questions is the most important influence on the answers given to a sample survey. sampling frame - the list of individuals from which a sample is actually selected is called the________ Placebo effect - a dummy treatment. control group - it enables us to control the effects of lurking variable on the outcome