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Tables and Formulas in Introduction to Statistics Cheat Sheet, Cheat Sheet of Statistics

Exploring and producing data, Probability and Sampling Distributions, Inference about Means etc concepts are part of this cheat sheet.

Typology: Cheat Sheet

2020/2021

Uploaded on 04/23/2021

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TABLES AND FORMULAS FOR MOORE
Basic Practice of Statistics
Exploring Data: Distributions
Look for overall pattern (shape, center, spread)
and deviations (outliers).
Mean (use a calculator):
x=x1+x2+···+xn
n=1
n!xi
Standard deviation (use a calculator):
s="1
n1!(xix)2
Median: Arrange all observations from smallest
to largest. The median Mis located (n+ 1)/2
observations from the beginning of this list.
Quartiles: The first quartile Q1is the median of
the observations whose position in the ordered
list is to the left of the location of the overall
median. The third quartile Q3is the median of
the observations to the right of the location of
the overall median.
Five-number summary:
Minimum, Q1, M, Q3,Maximum
Standardized value of x:
z=xµ
σ
Exploring Data: Relationships
Look for overall pattern (form, direction,
strength) and deviations (outliers, influential
observations).
Correlation (use a calculator):
r=1
n1!#xix
sx$%yiy
sy&
Least-squares regression line (use a calculator):
ˆy=a+bx with slope b=rsy/sxand intercept
a=ybx
Residuals:
residual = observed ypredicted y=yˆy
Producing Data
Simple random sample: Choose an SRS by giv-
ing every individual in the population a numer-
ical label and using Table B of random digits to
choose the sample.
Randomized comparative experiments:
Random
Allocation
!
!"
#
#$
Group 1
Group 2
%
%
Treatment 1
Treatment 2
#
#$
!
!"
Observe
Response
Probability and Sampling
Distributions
Probability rules:
Any probability satisfies 0 P(A)1.
The sample space Shas probability P(S) =
1.
For any event A,P(Adoes not occur) =
1P(A)
If events Aand Bare disjoint, P(Aor B) =
P(A) + P(B).
pf3
pf4
pf5

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TABLES AND FORMULAS FOR MOORE

Basic Practice of Statistics

Exploring Data: Distributions

• Look for overall pattern (shape, center, spread)

and deviations (outliers).

• Mean (use a calculator):

x =

x 1 + x 2 + · · · + xn

n

n

xi

• Standard deviation (use a calculator):

s =

n − 1

(xi − x)^2

• Median: Arrange all observations from smallest

to largest. The median M is located (n + 1)/ 2

observations from the beginning of this list.

• Quartiles: The first quartile Q 1 is the median of

the observations whose position in the ordered

list is to the left of the location of the overall

median. The third quartile Q 3 is the median of

the observations to the right of the location of

the overall median.

• Five-number summary:

Minimum, Q 1 , M, Q 3 , Maximum

• Standardized value of x:

z =

x − μ

Exploring Data: Relationships

• Look for overall pattern (form, direction,

strength) and deviations (outliers, influential

observations).

• Correlation (use a calculator):

r =

n − 1

∑ (^ xi − x

sx

) (^

y i − y

sy

• Least-squares regression line (use a calculator):

yˆ = a + bx with slope b = rsy /sx and intercept

a = y − bx

• Residuals:

residual = observed y − predicted y = y − yˆ

Producing Data

• Simple random sample: Choose an SRS by giv-

ing every individual in the population a numer-

ical label and using Table B of random digits to

choose the sample.

• Randomized comparative experiments:

Random

Allocation

Group 1

Group 2

Treatment 1

Treatment 2

Observe

Response

Probability and Sampling

Distributions

• Probability rules:

• Any probability satisfies 0 ≤ P (A) ≤ 1.

• The sample space S has probability P (S) =

• For any event A, P (A does not occur) =

1 − P (A)

• If events A and B are disjoint, P (A or B) =

P (A) + P (B).

  • Sampling distribution of a sample mean:
    • x has mean μ and standard deviation σ/

√ n.

  • x has a Normal distribution if the popula- tion distribution is Normal.
  • Central limit theorem: x is approximately Normal when n is large.

Basics of Inference

  • z confidence interval for a population mean

(σ known, SRS from Normal population):

x ± z ∗^

σ √ n

z ∗^ from N (0, 1)

  • Sample size for desired margin of error m:

n =

z ∗^ σ

m

  • z test statistic for H 0 : μ = μ 0 (σ known, SRS

from Normal population):

z =

x − μ 0

σ/

√ n

P -values from N (0, 1)

Inference About Means

  • t confidence interval for a population mean (SRS

from Normal population):

x ± t

∗ (^) √s n

t

from t(n − 1)

  • t test statistic for H 0 : μ = μ 0 (SRS from Normal

population):

t =

x − μ 0

s/

√ n

P -values from t(n − 1)

  • Matched pairs: To compare the responses to the

two treatments, apply the one-sample t proce-

dures to the observed differences.

  • Two-sample t confidence interval for μ 1 − μ 2 (in-

dependent SRSs from Normal populations):

(x 1 − x 2 ) ± t

s^21

n (^1)

s^22

n (^2)

with conservative t ∗^ from t with df the smaller of n 1 − 1 and n 2 − 1 (or use software).

  • Two-sample t test statistic for H 0 : μ 1 = μ 2

(independent SRSs from Normal populations):

t =

x 1 − x 2

s^21

n (^1)

s^22

n (^2)

with conservative P -values from t with df the smaller of n 1 − 1 and n 2 − 1 (or use software).

Inference About Proportions

  • Sampling distribution of a sample proportion:

when the population and the sample size are both large and p is not close to 0 or 1, ˆp is ap-

proximately Normal with mean p and standard deviation

p(1 − p)/n.

  • Large-sample z confidence interval for p:

pˆ ± z ∗

p ˆ(1 − pˆ)

n

z ∗^ from N (0, 1)

Plus four to greatly improve accuracy: use the

same formula after adding 2 successes and two failures to the data.

  • z test statistic for H 0 : p = p 0 (large SRS):

z =

pˆ − p (^0)

p 0 (1 − p 0 )

n

P -values from N (0, 1)

  • Sample size for desired margin of error m:

n =

z ∗

m

p

(1 − p

)

where p ∗^ is a guessed value for p or p∗^ = 0.5.

  • Large-sample z confidence interval for p 1 − p 2 :

(ˆp 1 − pˆ 2 ) ± z

SE z

from N (0, 1)

where the standard error of ˆp 1 − pˆ 2 is

SE =

p ˆ 1 (1 − pˆ 1 )

n (^1)

pˆ 2 (1 − pˆ 2 )

n (^2)

Plus four to greatly improve accuracy: use the

same formulas after adding one success and one failure to each sample.

TABLE A Standard Normal probabilities

TABLE B Random digits Line 101 19223 95034 05756 28713 96409 12531 42544 82853 102 73676 47150 99400 01927 27754 42648 82425 36290 103 45467 71709 77558 00095 32863 29485 82226 90056 104 52711 38889 93074 60227 40011 85848 48767 52573 105 95592 94007 69971 91481 60779 53791 17297 59335 106 68417 35013 15529 72765 85089 57067 50211 47487 107 82739 57890 20807 47511 81676 55300 94383 14893 108 60940 72024 17868 24943 61790 90656 87964 18883 109 36009 19365 15412 39638 85453 46816 83485 41979 110 38448 48789 18338 24697 39364 42006 76688 08708 111 81486 69487 60513 09297 00412 71238 27649 39950 112 59636 88804 04634 71197 19352 73089 84898 45785 113 62568 70206 40325 03699 71080 22553 11486 11776 114 45149 32992 75730 66280 03819 56202 02938 70915 115 61041 77684 94322 24709 73698 14526 31893 32592 116 14459 26056 31424 80371 65103 62253 50490 61181 117 38167 98532 62183 70632 23417 26185 41448 75532 118 73190 32533 04470 29669 84407 90785 65956 86382 119 95857 07118 87664 92099 58806 66979 98624 84826 120 35476 55972 39421 65850 04266 35435 43742 11937 121 71487 09984 29077 14863 61683 47052 62224 51025 122 13873 81598 95052 90908 73592 75186 87136 95761 123 54580 81507 27102 56027 55892 33063 41842 81868 124 71035 09001 43367 49497 72719 96758 27611 91596 125 96746 12149 37823 71868 18442 35119 62103 39244

TABLE C t distribution critical values Upper tail probability p df .25 .20 .15 .10 .05 .025 .02 .01 .005 .0025 .001. 1 1.000 1.376 1.963 3.078 6.314 12.71 15.89 31.82 63.66 127.3 318.3 636. 2 0.816 1.061 1.386 1.886 2.920 4.303 4.849 6.965 9.925 14.09 22.33 31. 3 0.765 0.978 1.250 1.638 2.353 3.182 3.482 4.541 5.841 7.453 10.21 12. 4 0.741 0.941 1.190 1.533 2.132 2.776 2.999 3.747 4.604 5.598 7.173 8. 5 0.727 0.920 1.156 1.476 2.015 2.571 2.757 3.365 4.032 4.773 5.893 6. 6 0.718 0.906 1.134 1.440 1.943 2.447 2.612 3.143 3.707 4.317 5.208 5. 7 0.711 0.896 1.119 1.415 1.895 2.365 2.517 2.998 3.499 4.029 4.785 5. 8 0.706 0.889 1.108 1.397 1.860 2.306 2.449 2.896 3.355 3.833 4.501 5. 9 0.703 0.883 1.100 1.383 1.833 2.262 2.398 2.821 3.250 3.690 4.297 4. 10 0.700 0.879 1.093 1.372 1.812 2.228 2.359 2.764 3.169 3.581 4.144 4. 11 0.697 0.876 1.088 1.363 1.796 2.201 2.328 2.718 3.106 3.497 4.025 4. 12 0.695 0.873 1.083 1.356 1.782 2.179 2.303 2.681 3.055 3.428 3.930 4. 13 0.694 0.870 1.079 1.350 1.771 2.160 2.282 2.650 3.012 3.372 3.852 4. 14 0.692 0.868 1.076 1.345 1.761 2.145 2.264 2.624 2.977 3.326 3.787 4. 15 0.691 0.866 1.074 1.341 1.753 2.131 2.249 2.602 2.947 3.286 3.733 4. 16 0.690 0.865 1.071 1.337 1.746 2.120 2.235 2.583 2.921 3.252 3.686 4. 17 0.689 0.863 1.069 1.333 1.740 2.110 2.224 2.567 2.898 3.222 3.646 3. 18 0.688 0.862 1.067 1.330 1.734 2.101 2.214 2.552 2.878 3.197 3.611 3. 19 0.688 0.861 1.066 1.328 1.729 2.093 2.205 2.539 2.861 3.174 3.579 3. 20 0.687 0.860 1.064 1.325 1.725 2.086 2.197 2.528 2.845 3.153 3.552 3. 21 0.686 0.859 1.063 1.323 1.721 2.080 2.189 2.518 2.831 3.135 3.527 3. 22 0.686 0.858 1.061 1.321 1.717 2.074 2.183 2.508 2.819 3.119 3.505 3. 23 0.685 0.858 1.060 1.319 1.714 2.069 2.177 2.500 2.807 3.104 3.485 3. 24 0.685 0.857 1.059 1.318 1.711 2.064 2.172 2.492 2.797 3.091 3.467 3. 25 0.684 0.856 1.058 1.316 1.708 2.060 2.167 2.485 2.787 3.078 3.450 3. 26 0.684 0.856 1.058 1.315 1.706 2.056 2.162 2.479 2.779 3.067 3.435 3. 27 0.684 0.855 1.057 1.314 1.703 2.052 2.158 2.473 2.771 3.057 3.421 3. 28 0.683 0.855 1.056 1.313 1.701 2.048 2.154 2.467 2.763 3.047 3.408 3. 29 0.683 0.854 1.055 1.311 1.699 2.045 2.150 2.462 2.756 3.038 3.396 3. 30 0.683 0.854 1.055 1.310 1.697 2.042 2.147 2.457 2.750 3.030 3.385 3. 40 0.681 0.851 1.050 1.303 1.684 2.021 2.123 2.423 2.704 2.971 3.307 3. 50 0.679 0.849 1.047 1.299 1.676 2.009 2.109 2.403 2.678 2.937 3.261 3. 60 0.679 0.848 1.045 1.296 1.671 2.000 2.099 2.390 2.660 2.915 3.232 3. 80 0.678 0.846 1.043 1.292 1.664 1.990 2.088 2.374 2.639 2.887 3.195 3. 100 0.677 0.845 1.042 1.290 1.660 1.984 2.081 2.364 2.626 2.871 3.174 3. 1000 0.675 0.842 1.037 1.282 1.646 1.962 2.056 2.330 2.581 2.813 3.098 3. z ∗^ 0.674 0.841 1.036 1.282 1.645 1.960 2.054 2.326 2.576 2.807 3.091 3. 50% 60% 70% 80% 90% 95% 96% 98% 99% 99.5% 99.8% 99.9% Confidence level C