Stats_Exam1 Flashcards
What type of data is collected through a count?
Discrete quantitative
What type of data is collected through measurement
Continuous quantitative
What type of data is categorical?
Qualitative
What are the 3 principles of experimental design?
- Control
- Randomization
- Replication
What is the difference between observation and experiment
- o= observe + take measurements, data that already exists
- e= impose treatments and controls// one variable is the cause of changes
This is an experimental condition that determine the levels of single/multifactors
experimental treatment
What is the sampling method used to eliminate bias?
Simple Random Samples (SRS)
What are 3 biased sampling schemes?
convenience sampling, voluntary response sampling, nonresponse sampling
A call-in radio show that solicit audience participation in surveys on controversial topics like abortion is an example of
voluntary response sample
This is a variable that is not the explanatory variable but is thought to affect the response variable
Confounding, lurking
When can confounding variables be a problem?
- The results show a false correlation btwn dependent and independent variables,
- Null hypothesis.
Why is control, randomization, + replication important?
differences in the results of an experiment are not attributed to chance but are caused by treatments.
How do you look at a histogram and find the median
- write the values on the graph
- Add them up
- +1
- divided by 2
Which measure of center is NOT resistant to outliers- Median or Mean?
The Mean
What does the z score measure?
whether the data value is above or below average in standard deviations
What is the symbol for correlation
r
In a scatter plot- what does it mean when the data points are spread apart
r value further away from 1
What types of variables must you use to compute the r value
quantitative values
What do the regression line and the correlation have in common?
both have the same sign (neg or pos)
What is included in a 5 number summary
- Min
- IQ1
- Median
- IQ3
- Max
If the scatter plot is curved is the regression line and r value appropriate?
no
What are the 3 percentages affiliated with the empirical rule? (if histogram is bell shaped)
68
95
99.7
How many standard deviations is 68% away from the mean?
1
How many standard deviations is 95% away from the mean?
2
