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
How many standard deviations is 99.7% away from the mean?
3
What is the formula for the z score?
individual- pop mean / standard deviation
What is the value you get in the z-score mean
it is the number of standard deviations= correspons with the s.d. value
What are the steps to determine an outlier?
- IQR x 1.5
- Add that value to Q3
- Add value to Q1
- Evaluate new range and compare
What must you do before graphing a box plot?
determine if there are any outliers
In terms of scatter plot, what does bivariate mean?
2 quantitative variables being compared
Which value is the slope b0 or b1?
b1
How do you compute the y-intercept?
b0= yavg- ( b1 * xavg)
What tables do you need to get the sum for b1?
x, y, x - xavg, y - yavg, x - xavg2, y - yavg2
Sxy/Sxx
In the error sum of squares what new value are you computing?
the comparison of y actual and y with the equation
What does r2 measure
the percent of variation explained by observed values in response to the regression
the total sum of squares
is the total sum of variation in the response variable.
SSR or regression sum of squares
the variation explained by the regression
What indicates a strong linear relationship of r
value close to -1 or 1
