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Coconino Community College
coconino.edu › resources › files › pdfs › academics › sabbatical-reports › kate-kozak › appendix_table.pdf pdf
Appendix: Critical Values Tables 433 Appendix: Critical Value Tables
Table A.1: Normal Critical Values for Confidence Levels · Table A.2: Critical Values for t-Interval · Appendix: Critical Values Tables · 434 · Table A.1: Normal Critical Values for Confidence Levels · Confidence Level, C · Critical Value, zc · 99% 2.575 · 98% 2.33 ·
Discussions

Can somebody help me understand calculating critical values for a confidence interval? (stats)
You can find the 10th percentile of Z, -1.28, and then ignore the negative sign More on reddit.com
🌐 r/learnmath
3
4
August 5, 2024
Confidence Intervals within Pivot Table?
Not having a whole lot of luck finding much information on CI's with pivot tables, I did find this blog post that might help you out: Statistics: PivotTable More on reddit.com
🌐 r/excel
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November 28, 2012
finding the critical value a confidence interval that is not on my table
"za/2 = 0.0125". That should just be α/2 = 0.0125. You're dealing with tail probability not z-value In this specific question, degrees of freedom are not required. Can you clarify what you mean by this? Every t-distribution has a degrees of freedom parameter, so you must have something to look up there. Do you mean that the d.f. are large enough to use a normal approximation? If so, just use normal tables. More on reddit.com
🌐 r/AskStatistics
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0
July 31, 2018
How to find a z-value in table given the confidence interval
5% in each tail mean the probability that the true value is outside the confidence interval, for each side, is 5%. Look up the table. The table tell you, for each z-value, the corresponding one-sided tail probability, so look up the number closest to 5% and read off the z-value from the sides. If the exam ask for 93%, do similarly. If you have the one-sided table, but the confidence interval is 2-sided, then you need to find one-sided tail probability, which is 3.5%, then look up the number closest to 3.5% on that table and read off the z-value. More on reddit.com
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5
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November 9, 2019
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Crafton Hills College
craftonhills.edu › current-students › tutoring-center › mathematics-tutoring › distribution_tables_normal_studentt_chisquared.pdf pdf
Confidence Interval Critical Values, zα/2 Level of Confidence
Standard Normal Distribution Probabilities Table · one-tail area · 0.25 · 0.125 · 0.1 · 0.075 · 0.05 · 0.025 · 0.01 · 0.005 · 0.0005 · two-tail area · 0.5 · 0.25 · 0.2 · 0.15 · 0.1 · 0.05 · 0.02 · 0.01 · 0.001 · confidence level · 0.5 · 0.75 ·
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University of Regina
uregina.ca › ~gingrich › tt.pdf pdf
t-distribution Confidence Level 60% 70% 80% 85% 90% 95% 98% 99% 99.8% 99.9%
Confidence Level · 60% 70% 80% 85% 90% 95% 98% 99% 99.8% 99.9% Level of Significance · 2 Tailed · 0.40 · 0.30 · 0.20 · 0.15 · 0.10 · 0.05 · 0.02 · 0.01 · 0.002 · 0.001 · 1 Tailed · 0.20 · 0.15 · 0.10 · 0.075 · 0.05 · 0.025 · 0.01 · 0.005 ·
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YouTube
youtube.com › patrick j
Constructing Confidence Intervals - YouTube
Constructing Confidence Intervals
Published   January 23, 2025
Views   1K
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Utoronto
sites.chem.utoronto.ca › chemistry › coursenotes › analsci › stats › ttesttable.html
Table of Critical t-Values for 95% Confidence Level
Table of critical values for a 2-tailed t-test at 95% confidence level, generated from Excel using the TINV function.
Find elsewhere
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APA Style
apastyle.apa.org › style-grammar-guidelines › tables-figures › sample-tables
Sample tables
Note. Number of studies = 120, number of effects = 782, total N = 52,578. CI = confidence interval; LL = lower limit; UL = upper limit. a 0 = self-report, 1 = test. b 0 = test, 1 = grade point average. c Study year was grand centered. d 0 = other, 1 = yes.
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Wikipedia
en.wikipedia.org › wiki › Confidence_interval
Confidence interval - Wikipedia
October 29, 2025 - In other words, if the same sampling procedure were repeated 100 times from the same population, approximately 95 of the resulting intervals would be expected to contain the true population mean. ... {\displaystyle \varphi } includes other parameters (if any) that determine the distribution. A confidence interval for the parameter
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Dummies
dummies.com › article › academics-the-arts › math › statistics › how-to-find-t-values-for-confidence-intervals-169841
How to Find t-Values for Confidence Intervals
July 2, 2025 - To help you find critical values for the t-distribution, you can use the last row of the t-table, which lists common confidence levels, such as 80%, 90%, and 95%. To find a critical value, look up your confidence level in the bottom row of the table; this tells you which column of the t-table you need. Intersect this column with the row for your df (degrees of freedom). The number you see is the critical value (or the t-value) for your confidence interval.
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Scribbr
scribbr.com › home › understanding confidence intervals | easy examples & formulas
Understanding Confidence Intervals | Easy Examples & Formulas
June 22, 2023 - Check out this set of t tables to find your t statistic. We have included the confidence level and p values for both one-tailed and two-tailed tests to help you find the t value you need.
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Statistics How To
statisticshowto.com › home › probability and statistics topics index › confidence interval: definition, examples
Confidence Interval: Definition, Examples - Statistics How To
June 26, 2025 - Find a confidence interval for a sample for the true mean weight of all foot surgery patients. Use a 95% CL. ... Subtract 1 from your sample size. 10 – 1 = 9. This gives you degrees of freedom, which you’ll need in step 3. Subtract the confidence level from 1, then divide by two. (1 – .95) / 2 = .025 · Look up your answers to step 1 and 2 in the t-distribution table.
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Simon Fraser University
sfu.ca › sasdoc › sashtml › insight › chap38 › sect12.htm
Basic Confidence Intervals
Assuming that the population is normally distributed, the Confidence Intervals table gives confidence intervals for the mean, standard deviation, and variance at the confidence coefficient specified.
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Reddit
reddit.com › r/learnmath › can somebody help me understand calculating critical values for a confidence interval? (stats)
r/learnmath on Reddit: Can somebody help me understand calculating critical values for a confidence interval? (stats)
August 5, 2024 -

Im so confused rn, I thought I understood this concept but it turns out not cause Im studying for the a stats test and one of the questions it says the critical value for a Confidence Interval of 80% is 1.28 and I don't understand why.

Their reasoning is 1 - .80 = .20, divded by two to get the area of the tails is .10, so then they add one of the tails (.10) to .80 which gets .90 and then they find that on the normal table which correlates to 1.28.

The way I have been doing is like this, 1 - .80= .20, and then divided by two is .10. So then I just need to find .10 in the normal table. Thats how they say to do it on youtube and it has been working for me up until now, I dont understand why they add .10 to .8 and why it doesnt say to do that in any video.

Can somebody pls help me understand it would be much appreciated, I have a test coming up and this is the only thing I cannot grasp .

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Texas Tech University
math.ttu.edu › ~lellings › 3342 › Table-Critical-Values.pdf pdf
Table entry for C is the critical value t∗required for confidence
TABLE C t distribution critical values · CONFIDENCE LEVEL C · DEGREES OF · FREEDOM · 50% 60% 70% 80% 90% 95% 96% 98% 99% 99.5% 99.8% 99.9% 1 · 1.000 · 1.376 · 1.963 · 3.078 · 6.314 · 12.71 · 15.89 · 31.82 · 63.66 · 127.3 · 318.3 · 636.6 · 2 · 0.816 ·
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Colorado State University
stat.colostate.edu › inmem › gumina › st201 › pdf › Utts-Heckard_t-Table.pdf pdf
0 t critical value -t critical value t curve Central area t critical values
Confidence area captured: 0.90 · 0.95 · 0.98 · 0.99 · Confidence level: 90% 95% 98% 99% 1 · 6.31 · 12.71 · 31.82 · 63.66 · 2 · 2.92 · 4.30 · 6.97 · 9.93 · 3 · 2.35 · 3.18 · 4.54 · 5.84 · 4 · 2.13 · 2.78 · 3.75 · 4.60 · 5 · 2.02 · 2.57 ·