How to report t statistic from R Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 23, 2019 at 00:00UTC (8:00pm US/Eastern)two-sample t-test VS two one-sample t-tests. What's the difference?non parametric or parametric test for means of groups?How to test difference from 50%Predicting population mean and variance based on sample mean and varianceInconsistent results with median test (Coin-package) RDifferent results with repeated measure correlation (rmcorr) and cor.testHow to interpret Wilcoxon test for small difference in location?What to report for Bootstrapping?Do we assume a t distribution for the estimate of the difference of normal distributions?How to interpret results on different t-tests for the same samples?

What does it mean that physics no longer uses mechanical models to describe phenomena?

AppleTVs create a chatty alternate WiFi network

A letter with no particular backstory

The Nth Gryphon Number

Lagrange four-squares theorem --- deterministic complexity

A term for a woman complaining about things/begging in a cute/childish way

What does this say in Elvish?

How do living politicians protect their readily obtainable signatures from misuse?

Why do early math courses focus on the cross sections of a cone and not on other 3D objects?

Central Vacuuming: Is it worth it, and how does it compare to normal vacuuming?

How were pictures turned from film to a big picture in a picture frame before digital scanning?

How much damage would a cupful of neutron star matter do to the Earth?

How fail-safe is nr as stop bytes?

Is multiple magic items in one inherently imbalanced?

What makes a man succeed?

What does Turing mean by this statement?

Is there hard evidence that the grant peer review system performs significantly better than random?

How does light 'choose' between wave and particle behaviour?

Unit testing extension method adding view location expander

How to write capital alpha?

What would you call this weird metallic apparatus that allows you to lift people?

Random body shuffle every night—can we still function?

Maximum summed subsequences with non-adjacent items

Flash light on something



How to report t statistic from R



Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 23, 2019 at 00:00UTC (8:00pm US/Eastern)two-sample t-test VS two one-sample t-tests. What's the difference?non parametric or parametric test for means of groups?How to test difference from 50%Predicting population mean and variance based on sample mean and varianceInconsistent results with median test (Coin-package) RDifferent results with repeated measure correlation (rmcorr) and cor.testHow to interpret Wilcoxon test for small difference in location?What to report for Bootstrapping?Do we assume a t distribution for the estimate of the difference of normal distributions?How to interpret results on different t-tests for the same samples?



.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








2












$begingroup$


I'm wondering how to report the result of a t-test from R given that the degrees of freedom change when the lengths of the vectors are the same.



For example



set.seed(1)
n = 500
x = rnorm(n, 6, 1)
y = rnorm(n, 6, 2)
t = t.test(x,y)
t
t$parameter


Gives the output



> t

Welch Two Sample t-test

data: x and y
t = 1.0924, df = 716.16, p-value = 0.275
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
-0.09130295 0.32035262
sample estimates:
mean of x mean of y
6.022644 5.908119

> t$parameter
df
716.156


Whereas



set.seed(2)
n = 500
x = rnorm(n, 6, 1)
y = rnorm(n, 6, 2)
t = t.test(x,y)
t
t$parameter


Gives the output



> t

Welch Two Sample t-test

data: x and y
t = -0.62595, df = 748.05, p-value = 0.5315
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
-0.2602459 0.1344099
sample estimates:
mean of x mean of y
6.061692 6.124610

> t$parameter
df
748.0475


I'm not sure if it would be typical to report the first as $t(716.15), p = 0.275$ and the second as $t(748.05), p = 0.53$










share|cite|improve this question











$endgroup$


















    2












    $begingroup$


    I'm wondering how to report the result of a t-test from R given that the degrees of freedom change when the lengths of the vectors are the same.



    For example



    set.seed(1)
    n = 500
    x = rnorm(n, 6, 1)
    y = rnorm(n, 6, 2)
    t = t.test(x,y)
    t
    t$parameter


    Gives the output



    > t

    Welch Two Sample t-test

    data: x and y
    t = 1.0924, df = 716.16, p-value = 0.275
    alternative hypothesis: true difference in means is not equal to 0
    95 percent confidence interval:
    -0.09130295 0.32035262
    sample estimates:
    mean of x mean of y
    6.022644 5.908119

    > t$parameter
    df
    716.156


    Whereas



    set.seed(2)
    n = 500
    x = rnorm(n, 6, 1)
    y = rnorm(n, 6, 2)
    t = t.test(x,y)
    t
    t$parameter


    Gives the output



    > t

    Welch Two Sample t-test

    data: x and y
    t = -0.62595, df = 748.05, p-value = 0.5315
    alternative hypothesis: true difference in means is not equal to 0
    95 percent confidence interval:
    -0.2602459 0.1344099
    sample estimates:
    mean of x mean of y
    6.061692 6.124610

    > t$parameter
    df
    748.0475


    I'm not sure if it would be typical to report the first as $t(716.15), p = 0.275$ and the second as $t(748.05), p = 0.53$










    share|cite|improve this question











    $endgroup$














      2












      2








      2





      $begingroup$


      I'm wondering how to report the result of a t-test from R given that the degrees of freedom change when the lengths of the vectors are the same.



      For example



      set.seed(1)
      n = 500
      x = rnorm(n, 6, 1)
      y = rnorm(n, 6, 2)
      t = t.test(x,y)
      t
      t$parameter


      Gives the output



      > t

      Welch Two Sample t-test

      data: x and y
      t = 1.0924, df = 716.16, p-value = 0.275
      alternative hypothesis: true difference in means is not equal to 0
      95 percent confidence interval:
      -0.09130295 0.32035262
      sample estimates:
      mean of x mean of y
      6.022644 5.908119

      > t$parameter
      df
      716.156


      Whereas



      set.seed(2)
      n = 500
      x = rnorm(n, 6, 1)
      y = rnorm(n, 6, 2)
      t = t.test(x,y)
      t
      t$parameter


      Gives the output



      > t

      Welch Two Sample t-test

      data: x and y
      t = -0.62595, df = 748.05, p-value = 0.5315
      alternative hypothesis: true difference in means is not equal to 0
      95 percent confidence interval:
      -0.2602459 0.1344099
      sample estimates:
      mean of x mean of y
      6.061692 6.124610

      > t$parameter
      df
      748.0475


      I'm not sure if it would be typical to report the first as $t(716.15), p = 0.275$ and the second as $t(748.05), p = 0.53$










      share|cite|improve this question











      $endgroup$




      I'm wondering how to report the result of a t-test from R given that the degrees of freedom change when the lengths of the vectors are the same.



      For example



      set.seed(1)
      n = 500
      x = rnorm(n, 6, 1)
      y = rnorm(n, 6, 2)
      t = t.test(x,y)
      t
      t$parameter


      Gives the output



      > t

      Welch Two Sample t-test

      data: x and y
      t = 1.0924, df = 716.16, p-value = 0.275
      alternative hypothesis: true difference in means is not equal to 0
      95 percent confidence interval:
      -0.09130295 0.32035262
      sample estimates:
      mean of x mean of y
      6.022644 5.908119

      > t$parameter
      df
      716.156


      Whereas



      set.seed(2)
      n = 500
      x = rnorm(n, 6, 1)
      y = rnorm(n, 6, 2)
      t = t.test(x,y)
      t
      t$parameter


      Gives the output



      > t

      Welch Two Sample t-test

      data: x and y
      t = -0.62595, df = 748.05, p-value = 0.5315
      alternative hypothesis: true difference in means is not equal to 0
      95 percent confidence interval:
      -0.2602459 0.1344099
      sample estimates:
      mean of x mean of y
      6.061692 6.124610

      > t$parameter
      df
      748.0475


      I'm not sure if it would be typical to report the first as $t(716.15), p = 0.275$ and the second as $t(748.05), p = 0.53$







      r hypothesis-testing t-test reporting






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited 44 mins ago









      Karolis Koncevičius

      2,39341630




      2,39341630










      asked 1 hour ago









      baxxbaxx

      310111




      310111




















          2 Answers
          2






          active

          oldest

          votes


















          2












          $begingroup$

          If you have to report all the details then you should also report the actual t-value, not just degrees of freedom.



          About the degrees of freedom: your degrees of freedom changes because you are using t-test with Welch correction for pooling the variances of the two groups. If your context permits to assume equal variances in both groups you could call the t.test() in the following way:



          t.test(x, y, var.equal=TRUE)


          then you would get the same degrees of freedom for both cases - a whole number dependant on the number of observations. However don't do this just to get a round degrees of freedom value.



          And if Welch t-test is more appropriate in your case consider stating that Welch t-test was used in your report as well.






          share|cite|improve this answer









          $endgroup$




















            2












            $begingroup$

            The Student's t-test assumes both samples having the same variance and in this case the degrees of freedom are simply n1 + n2 - 2. On the other hand, the Welch test does mot make this assumption and in this case you have to calculate the degrees of freedom where the variances of the samples are considered and thus you do not always get the same degrees of freedom for the same sample size. The answer is to report the degrees of freedom as you did (reading it up from the R output).



            EDIT



            I agree with Karolis Koncevičius that you need to report the t value as well, of course. For your first example you would report t(716.16)= 1.09, p= 0.275. Although it depends on the citing format in your discipline how many decimal places you need to report, for example. But I would suggest using the Welch t test as default as it is the case in R "because Welch's t-test performs better than Student's t-test whenever sample sizes and variances are unequal between groups, and gives the same result when sample sizes and variances are equal." (quote from source in link before).






            share|cite|improve this answer










            New contributor




            stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.






            $endgroup$













              Your Answer








              StackExchange.ready(function()
              var channelOptions =
              tags: "".split(" "),
              id: "65"
              ;
              initTagRenderer("".split(" "), "".split(" "), channelOptions);

              StackExchange.using("externalEditor", function()
              // Have to fire editor after snippets, if snippets enabled
              if (StackExchange.settings.snippets.snippetsEnabled)
              StackExchange.using("snippets", function()
              createEditor();
              );

              else
              createEditor();

              );

              function createEditor()
              StackExchange.prepareEditor(
              heartbeatType: 'answer',
              autoActivateHeartbeat: false,
              convertImagesToLinks: false,
              noModals: true,
              showLowRepImageUploadWarning: true,
              reputationToPostImages: null,
              bindNavPrevention: true,
              postfix: "",
              imageUploader:
              brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
              contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
              allowUrls: true
              ,
              onDemand: true,
              discardSelector: ".discard-answer"
              ,immediatelyShowMarkdownHelp:true
              );



              );













              draft saved

              draft discarded


















              StackExchange.ready(
              function ()
              StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstats.stackexchange.com%2fquestions%2f404032%2fhow-to-report-t-statistic-from-r%23new-answer', 'question_page');

              );

              Post as a guest















              Required, but never shown

























              2 Answers
              2






              active

              oldest

              votes








              2 Answers
              2






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              2












              $begingroup$

              If you have to report all the details then you should also report the actual t-value, not just degrees of freedom.



              About the degrees of freedom: your degrees of freedom changes because you are using t-test with Welch correction for pooling the variances of the two groups. If your context permits to assume equal variances in both groups you could call the t.test() in the following way:



              t.test(x, y, var.equal=TRUE)


              then you would get the same degrees of freedom for both cases - a whole number dependant on the number of observations. However don't do this just to get a round degrees of freedom value.



              And if Welch t-test is more appropriate in your case consider stating that Welch t-test was used in your report as well.






              share|cite|improve this answer









              $endgroup$

















                2












                $begingroup$

                If you have to report all the details then you should also report the actual t-value, not just degrees of freedom.



                About the degrees of freedom: your degrees of freedom changes because you are using t-test with Welch correction for pooling the variances of the two groups. If your context permits to assume equal variances in both groups you could call the t.test() in the following way:



                t.test(x, y, var.equal=TRUE)


                then you would get the same degrees of freedom for both cases - a whole number dependant on the number of observations. However don't do this just to get a round degrees of freedom value.



                And if Welch t-test is more appropriate in your case consider stating that Welch t-test was used in your report as well.






                share|cite|improve this answer









                $endgroup$















                  2












                  2








                  2





                  $begingroup$

                  If you have to report all the details then you should also report the actual t-value, not just degrees of freedom.



                  About the degrees of freedom: your degrees of freedom changes because you are using t-test with Welch correction for pooling the variances of the two groups. If your context permits to assume equal variances in both groups you could call the t.test() in the following way:



                  t.test(x, y, var.equal=TRUE)


                  then you would get the same degrees of freedom for both cases - a whole number dependant on the number of observations. However don't do this just to get a round degrees of freedom value.



                  And if Welch t-test is more appropriate in your case consider stating that Welch t-test was used in your report as well.






                  share|cite|improve this answer









                  $endgroup$



                  If you have to report all the details then you should also report the actual t-value, not just degrees of freedom.



                  About the degrees of freedom: your degrees of freedom changes because you are using t-test with Welch correction for pooling the variances of the two groups. If your context permits to assume equal variances in both groups you could call the t.test() in the following way:



                  t.test(x, y, var.equal=TRUE)


                  then you would get the same degrees of freedom for both cases - a whole number dependant on the number of observations. However don't do this just to get a round degrees of freedom value.



                  And if Welch t-test is more appropriate in your case consider stating that Welch t-test was used in your report as well.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered 1 hour ago









                  Karolis KoncevičiusKarolis Koncevičius

                  2,39341630




                  2,39341630























                      2












                      $begingroup$

                      The Student's t-test assumes both samples having the same variance and in this case the degrees of freedom are simply n1 + n2 - 2. On the other hand, the Welch test does mot make this assumption and in this case you have to calculate the degrees of freedom where the variances of the samples are considered and thus you do not always get the same degrees of freedom for the same sample size. The answer is to report the degrees of freedom as you did (reading it up from the R output).



                      EDIT



                      I agree with Karolis Koncevičius that you need to report the t value as well, of course. For your first example you would report t(716.16)= 1.09, p= 0.275. Although it depends on the citing format in your discipline how many decimal places you need to report, for example. But I would suggest using the Welch t test as default as it is the case in R "because Welch's t-test performs better than Student's t-test whenever sample sizes and variances are unequal between groups, and gives the same result when sample sizes and variances are equal." (quote from source in link before).






                      share|cite|improve this answer










                      New contributor




                      stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.






                      $endgroup$

















                        2












                        $begingroup$

                        The Student's t-test assumes both samples having the same variance and in this case the degrees of freedom are simply n1 + n2 - 2. On the other hand, the Welch test does mot make this assumption and in this case you have to calculate the degrees of freedom where the variances of the samples are considered and thus you do not always get the same degrees of freedom for the same sample size. The answer is to report the degrees of freedom as you did (reading it up from the R output).



                        EDIT



                        I agree with Karolis Koncevičius that you need to report the t value as well, of course. For your first example you would report t(716.16)= 1.09, p= 0.275. Although it depends on the citing format in your discipline how many decimal places you need to report, for example. But I would suggest using the Welch t test as default as it is the case in R "because Welch's t-test performs better than Student's t-test whenever sample sizes and variances are unequal between groups, and gives the same result when sample sizes and variances are equal." (quote from source in link before).






                        share|cite|improve this answer










                        New contributor




                        stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                        Check out our Code of Conduct.






                        $endgroup$















                          2












                          2








                          2





                          $begingroup$

                          The Student's t-test assumes both samples having the same variance and in this case the degrees of freedom are simply n1 + n2 - 2. On the other hand, the Welch test does mot make this assumption and in this case you have to calculate the degrees of freedom where the variances of the samples are considered and thus you do not always get the same degrees of freedom for the same sample size. The answer is to report the degrees of freedom as you did (reading it up from the R output).



                          EDIT



                          I agree with Karolis Koncevičius that you need to report the t value as well, of course. For your first example you would report t(716.16)= 1.09, p= 0.275. Although it depends on the citing format in your discipline how many decimal places you need to report, for example. But I would suggest using the Welch t test as default as it is the case in R "because Welch's t-test performs better than Student's t-test whenever sample sizes and variances are unequal between groups, and gives the same result when sample sizes and variances are equal." (quote from source in link before).






                          share|cite|improve this answer










                          New contributor




                          stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                          Check out our Code of Conduct.






                          $endgroup$



                          The Student's t-test assumes both samples having the same variance and in this case the degrees of freedom are simply n1 + n2 - 2. On the other hand, the Welch test does mot make this assumption and in this case you have to calculate the degrees of freedom where the variances of the samples are considered and thus you do not always get the same degrees of freedom for the same sample size. The answer is to report the degrees of freedom as you did (reading it up from the R output).



                          EDIT



                          I agree with Karolis Koncevičius that you need to report the t value as well, of course. For your first example you would report t(716.16)= 1.09, p= 0.275. Although it depends on the citing format in your discipline how many decimal places you need to report, for example. But I would suggest using the Welch t test as default as it is the case in R "because Welch's t-test performs better than Student's t-test whenever sample sizes and variances are unequal between groups, and gives the same result when sample sizes and variances are equal." (quote from source in link before).







                          share|cite|improve this answer










                          New contributor




                          stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                          Check out our Code of Conduct.









                          share|cite|improve this answer



                          share|cite|improve this answer








                          edited 45 mins ago





















                          New contributor




                          stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                          Check out our Code of Conduct.









                          answered 1 hour ago









                          stats.and.rstats.and.r

                          514




                          514




                          New contributor




                          stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                          Check out our Code of Conduct.





                          New contributor





                          stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                          Check out our Code of Conduct.






                          stats.and.r is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                          Check out our Code of Conduct.



























                              draft saved

                              draft discarded
















































                              Thanks for contributing an answer to Cross Validated!


                              • Please be sure to answer the question. Provide details and share your research!

                              But avoid


                              • Asking for help, clarification, or responding to other answers.

                              • Making statements based on opinion; back them up with references or personal experience.

                              Use MathJax to format equations. MathJax reference.


                              To learn more, see our tips on writing great answers.




                              draft saved


                              draft discarded














                              StackExchange.ready(
                              function ()
                              StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstats.stackexchange.com%2fquestions%2f404032%2fhow-to-report-t-statistic-from-r%23new-answer', 'question_page');

                              );

                              Post as a guest















                              Required, but never shown





















































                              Required, but never shown














                              Required, but never shown












                              Required, but never shown







                              Required, but never shown

































                              Required, but never shown














                              Required, but never shown












                              Required, but never shown







                              Required, but never shown







                              Popular posts from this blog

                              Oświęcim Innehåll Historia | Källor | Externa länkar | Navigeringsmeny50°2′18″N 19°13′17″Ö / 50.03833°N 19.22139°Ö / 50.03833; 19.2213950°2′18″N 19°13′17″Ö / 50.03833°N 19.22139°Ö / 50.03833; 19.221393089658Nordisk familjebok, AuschwitzInsidan tro och existensJewish Community i OświęcimAuschwitz Jewish Center: MuseumAuschwitz Jewish Center

                              Valle di Casies Indice Geografia fisica | Origini del nome | Storia | Società | Amministrazione | Sport | Note | Bibliografia | Voci correlate | Altri progetti | Collegamenti esterni | Menu di navigazione46°46′N 12°11′E / 46.766667°N 12.183333°E46.766667; 12.183333 (Valle di Casies)46°46′N 12°11′E / 46.766667°N 12.183333°E46.766667; 12.183333 (Valle di Casies)Sito istituzionaleAstat Censimento della popolazione 2011 - Determinazione della consistenza dei tre gruppi linguistici della Provincia Autonoma di Bolzano-Alto Adige - giugno 2012Numeri e fattiValle di CasiesDato IstatTabella dei gradi/giorno dei Comuni italiani raggruppati per Regione e Provincia26 agosto 1993, n. 412Heraldry of the World: GsiesStatistiche I.StatValCasies.comWikimedia CommonsWikimedia CommonsValle di CasiesSito ufficialeValle di CasiesMM14870458910042978-6

                              Typsetting diagram chases (with TikZ?) Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)How to define the default vertical distance between nodes?Draw edge on arcNumerical conditional within tikz keys?TikZ: Drawing an arc from an intersection to an intersectionDrawing rectilinear curves in Tikz, aka an Etch-a-Sketch drawingLine up nested tikz enviroments or how to get rid of themHow to place nodes in an absolute coordinate system in tikzCommutative diagram with curve connecting between nodesTikz with standalone: pinning tikz coordinates to page cmDrawing a Decision Diagram with Tikz and layout manager