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Summer 2014 > Stats_Exam1 > Flashcards

Stats_Exam1 Flashcards

1
Q

What type of data is collected through a count?

A

Discrete quantitative

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2
Q

What type of data is collected through measurement

A

Continuous quantitative

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3
Q

What type of data is categorical?

A

Qualitative

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4
Q

What are the 3 principles of experimental design?

A
  1. Control
  2. Randomization
  3. Replication
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5
Q

What is the difference between observation and experiment

A
  • o= observe + take measurements, data that already exists
  • e= impose treatments and controls// one variable is the cause of changes
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6
Q

This is an experimental condition that determine the levels of single/multifactors

A

experimental treatment

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7
Q

What is the sampling method used to eliminate bias?

A

Simple Random Samples (SRS)

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8
Q

What are 3 biased sampling schemes?

A

convenience sampling, voluntary response sampling, nonresponse sampling

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9
Q

A call-in radio show that solicit audience participation in surveys on controversial topics like abortion is an example of

A

voluntary response sample

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10
Q

This is a variable that is not the explanatory variable but is thought to affect the response variable

A

Confounding, lurking

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11
Q

When can confounding variables be a problem?

A
  • The results show a false correlation btwn dependent and independent variables,
  • Null hypothesis.
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12
Q

Why is control, randomization, + replication important?

A

differences in the results of an experiment are not attributed to chance but are caused by treatments.

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13
Q

How do you look at a histogram and find the median

A
  1. write the values on the graph
  2. Add them up
  3. +1
  4. divided by 2
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14
Q

Which measure of center is NOT resistant to outliers- Median or Mean?

A

The Mean

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15
Q

What does the z score measure?

A

whether the data value is above or below average in standard deviations

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16
Q

What is the symbol for correlation

A

r

17
Q

In a scatter plot- what does it mean when the data points are spread apart

A

r value further away from 1

18
Q

What types of variables must you use to compute the r value

A

quantitative values

19
Q

What do the regression line and the correlation have in common?

A

both have the same sign (neg or pos)

20
Q

What is included in a 5 number summary

A
  1. Min
  2. IQ1
  3. Median
  4. IQ3
  5. Max
21
Q

If the scatter plot is curved is the regression line and r value appropriate?

A

no

22
Q

What are the 3 percentages affiliated with the empirical rule? (if histogram is bell shaped)

A

68

95

99.7

23
Q

How many standard deviations is 68% away from the mean?

A

1

24
Q

How many standard deviations is 95% away from the mean?

A

2

25
Q

How many standard deviations is 99.7% away from the mean?

A

3

26
Q

What is the formula for the z score?

A

individual- pop mean / standard deviation

27
Q

What is the value you get in the z-score mean

A

it is the number of standard deviations= correspons with the s.d. value

28
Q

What are the steps to determine an outlier?

A
  1. IQR x 1.5
  2. Add that value to Q3
  3. Add value to Q1
  4. Evaluate new range and compare
29
Q

What must you do before graphing a box plot?

A

determine if there are any outliers

30
Q

In terms of scatter plot, what does bivariate mean?

A

2 quantitative variables being compared

31
Q

Which value is the slope b0 or b1?

A

b1

32
Q

How do you compute the y-intercept?

A

b0= yavg- ( b1 * xavg)

33
Q

What tables do you need to get the sum for b1?

A

x, y, x - xavg, y - yavg, x - xavg2, y - yavg2

34
Q

Sxy/Sxx

A
35
Q

In the error sum of squares what new value are you computing?

A

the comparison of y actual and y with the equation

36
Q

What does r2 measure

A

the percent of variation explained by observed values in response to the regression

37
Q

the total sum of squares

A

is the total sum of variation in the response variable.

38
Q

SSR or regression sum of squares

A

the variation explained by the regression

39
Q

What indicates a strong linear relationship of r

A

value close to -1 or 1

Summer 2014 (6 decks)

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