proc phreg estimate statement exampleVetlanda friskola

proc phreg estimate statement exampleproc phreg estimate statement example

We could test for different age effects with an interaction term between gender and age. Be careful to order the coefficients to match the order of the model parameters in the procedure. This paper will discuss this question by using some examples. 1 Answer Sorted by: 3 I'm not into statistics, so I'm just guessing what value you mean - here's an example I think could help you: ods trace on; ods output ParameterEstimates=work.my_estimates_dataset; proc phreg data=sashelp.class; model age = height; run; ods trace off; This is using SAS Output Delivery System component of SAS/Base. Graphs of the Kaplan-Meier estimate of the survival function allow us to see how the survival function changes over time and are fortunately very easy to generate in SAS: The step function form of the survival function is apparent in the graph of the Kaplan-Meier estimate. class gender; class gender; Computing the Cell Means Using the ESTIMATE Statement Use the Class Level Information table which shows the design variable settings. You can perform hypothesis tests for the estimable functions, construct confidence limits, and obtain specific nonlinear transformations. There are two crucial parts to this: Write down the hypothesis to be tested or quantity to be estimated in terms of the model's parameters and simplify. Note that the difference in log odds is equivalent to the log of the odds ratio: So, by exponentiating the estimated difference in log odds, an estimate of the odds ratio is provided. When a subject dies at a particular time point, the step function drops, whereas in between failure times the graph remains flat. \[F(t) = 1 exp(-H(t))\] As before, it is vital to know the order of the design variables that are created for an effect so that you properly order the contrast coefficients in the CONTRAST statement. In particular we would like to highlight the following tables: Handily, proc phreg has pretty extensive graphing capabilities.< Below is the graph and its accompanying table produced by simply adding plots=survival to the proc phreg statement. The estimate of survival beyond 3 days based off this Nelson-Aalen estimate of the cumulative hazard would then be \(\hat S(3) = exp(-0.0385) = 0.9623\). The "Class Level Information" table shows the ordering of levels within variables. model lenfol*fstat(0) = gender|age bmi|bmi hr hrtime; run; The solution vector in PROC MIXED is requested with the SOLUTION option in the MODEL statement and appears as the Estimate column in the Solution for Fixed Effects table: For this model, the solution vector of parameter estimates contains 18 elements. This technique can detect many departures from the true model, such as incorrect functional forms of covariates (discussed in this section), violations of the proportional hazards assumption (discussed later), and using the wrong link function (not discussed). Phreg For Survival Analysis In Sas 9 has been minimal coverage in the available literature to9 guide researchers, practitioners, and students who wish to apply these methods to health-related areas of study. Finally, we strongly suspect that heart rate is predictive of survival, so we include this effect in the model as well. See, In most cases, models fit in PROC GLIMMIX using the RANDOM statement do not use a true log likelihood. Words in italic are new statements added to SAS version 9.22. Nevertheless, in both we can see that in these data, shorter survival times are more probable, indicating that the risk of heart attack is strong initially and tapers off as time passes. proc sgplot data = dfbeta; Expressing the above relationship as \(\frac{d}{dt}H(t) = h(t)\), we see that the hazard function describes the rate at which hazards are accumulated over time. 1. Instead, we need only assume that whatever the baseline hazard function is, covariate effects multiplicatively shift the hazard function and these multiplicative shifts are constant over time. Biometrics. The (Proportional Hazards Regression) PHREG semi-parametric procedure performs a regression analysis of survival data based on the Cox proportional hazards model. The HPREG Procedure The HPSPLIT Procedure The ICLIFETEST Procedure The ICPHREG Procedure The INBREED Procedure The IRT Procedure The KDE Procedure The KRIGE2D Procedure The LATTICE Procedure The LIFEREG Procedure The LIFETEST Procedure The LOESS Procedure The LOGISTIC Procedure The MCMC Procedure The MDS Procedure The MI Procedure We simply use the SAS procedure PHREG to obtain the final result. Now choose a coefficient vector, also with 18 elements, that will multiply the solution vector: Choose a coefficient of 1 for the intercept (), coefficients of (1 0 0 0 0) for the A term to pick up the 1 estimate, coefficients of (0 1) for the B term to pick up the 2 estimate, and coefficients of (0 1 0 0 0 0 0 0 0 0) for the A*B interaction term to pick up the 12 estimate. The value must be between 0 and 1. These two observations, id=89 and id=112, have very low but not unreasonable bmi scores, 15.9 and 14.8. Table 86.1: PROC PHREG Statement Options You can specify the following options in the PROC PHREG statement. The change in coding scheme does not affect how you specify the ODDSRATIO statement. For a more detailed definition of nested and nonnested models, see the Clarke (2001) reference cited in the sample program. Summing over the entire interval, then, we would expect to observe \(x\) failures, as \(\frac{x}{t}t = x\), (assuming repeated failures are possible, such that failing does not remove one from observation). It is calculated by integrating the hazard function over an interval of time: Let us again think of the hazard function, \(h(t)\), as the rate at which failures occur at time \(t\). For example, we execute the following SAS codes on the dummy ADTTE These statements include the LSMEANS, LSMESTIMATE, and SLICE statements that are available in many procedures. Thus, to pull out all 6 \(df\beta_j\), we must supply 6 variable names for these \(df\beta_j\). The first element is the estimate of the intercept, . When the procedure reports a log pseudo-likelihood you cannot construct a LR test to compare models. Above we described that integrating the pdf over some range yields the probability of observing \(Time\) in that range. The above relationship between the cdf and pdf also implies: In SAS, we can graph an estimate of the cdf using proc univariate. Construction and Computation of Estimable Functions, Specifies a list of values to divide the coefficients, Suppresses the automatic fill-in of coefficients for higher-order effects, Tunes the estimability checking difference, Determines the method for multiple comparison adjustment of estimates, Performs one-sided, lower-tailed inference, Adjusts multiplicity-corrected p-values further in a step-down fashion, Specifies values under the null hypothesis for tests, Performs one-sided, upper-tailed inference, Displays the correlation matrix of estimates, Displays the covariance matrix of estimates, Produces a joint or chi-square test for the estimable functions, Requests ODS statistical graphics if the analysis is sampling-based, Specifies the seed for computations that depend on random numbers. Consider a model for two factors: A with five levels and B with two levels: where i=1,2,,5, j=1,2, k=1, 2,,nij. label row-description <,row-description>. If the elements of are not specified for an effect that contains a specified effect, then the elements of the specified effect are distributed over the levels of the higher-order effect just as the GLM procedure does for its CONTRAST and ESTIMATE statements. We also calculate the hazard ratio between females and males, or \(\frac{HR(gender=1)}{HR(gender=0)}\) at ages 0, 20, 40, 60, and 80. Notice the additional option, We then specify the name of this dataset in the, We request separate lines for each age using, We request that SAS create separate survival curves by the, We also add the newly created time-varying covariate to the, Run a null Cox regression model by leaving the right side of equation empty on the, Save the martingale residuals to an output dataset using the, The fraction of the data contained in each neighborhood is determined by the, A desirable feature of loess smooth is that the residuals from the regression do not have any structure. Thus, each term in the product is the conditional probability of survival beyond time \(t_i\), meaning the probability of surviving beyond time \(t_i\), given the subject has survived up to time \(t_i\). It appears that for males the log hazard rate increases with each year of age by 0.07086, and this AGE effect is significant, AGE*GENDER term is negative, which means for females, the change in the log hazard rate per year of age is 0.07086-0.02925=0.04161. Maximum likelihood methods attempt to find the \(\beta\) values that maximize this likelihood, that is, the regression parameters that yield the maximum joint probability of observing the set of failure times with the associated set of covariate values. This is an extension of the nested effects that you can specify in other procedures such as GLM and LOGISTIC. The log-rank and Wilcoxon tests in the output table differ in the weights \(w_j\) used. This indicates that omitting bmi from the model causes those with low bmi values to modeled with too low a hazard rate (as the number of observed events is in excess of the expected number of events). Still, although their effects are strong, we believe the data for these outliers are not in error and the significance of all effects are unaffected if we exclude them, so we include them in the model. SAS Code from All of These Examples. All of those hazard rates are based on the same baseline hazard rate \(h_0(t_i)\), so we can simplify the above expression to: \[Pr(subject=2|failure=t_j)=\frac{exp(x_2\beta)}{exp(x_1\beta)+exp(x_2\beta)+exp(x_3\beta)}\]. However, it is quite possible that the hazard rate and the covariates do not have such a loglinear relationship. These provide some statistical background for survival analysis for the interested reader (and for the author of the seminar!). hrtime = hr*lenfol; Then, as before, subtracting the two coefficient vectors yields the coefficient vector for testing the difference of these two averages. The likelihood displacement score quantifies how much the likelihood of the model, which is affected by all coefficients, changes when the observation is left out. The same results can be obtained using the ESTIMATE statement in PROC GENMOD. Institute for Digital Research and Education. These are the equivalent PROC GENMOD statements: A More Complex Contrast with Effects Coding. One can request that SAS estimate the survival function by exponentiating the negative of the Nelson-Aalen estimator, also known as the Breslow estimator, rather than by the Kaplan-Meier estimator through the method=breslow option on the proc lifetest statement. This convention can affect the way in which you specify the matrix in your CONTRAST statement. data example8_1; set sec1_5; group1 = group - 1; run; proc phreg data = example8_1; model time*death (0)=group1; run; These may be either removed or expanded in the future. Using dummy coding, the right-hand side of the logistic model looks like it does when modeling a normally distributed response as in Example 1: where i=1,2,,5, j=1,2, k=1, 2,,Nij. The quantity value must be a positive number, with a default value of 1E4. Basing the test on the REML results is generally preferred. The CONTRAST statement below defines seven rows in L for the seven interaction parameters resulting in a 7 DF test that all interaction parameters are zero. Constant multiplicative changes in the hazard rate may instead be associated with constant multiplicative, rather than additive, changes in the covariate, and might follow this relationship: \[HR = exp(\beta_x(log(x_2)-log(x_1)) = exp(\beta_x(log\frac{x_2}{x_1}))\]. Indeed, exclusion of these two outliers causes an almost doubling of \(\hat{\beta}_{bmi}\), from -0.23323 to -0.39619. requests that each individual contrast (that is, each row, , of ) or exponentiated contrast () be estimated and tested. (1995). To do so: It appears that being in the hospital increases the hazard rate, but this is probably due to the fact that all patients were in the hospital immediately after heart attack, when they presumbly are most vulnerable. For example, the time interval represented by the first row is from 0 days to just before 1 day. The ESTIMATE statement provides a mechanism for obtaining custom hypothesis tests. In the following output, the first parameter of the treatment(diagnosis='complicated') effect tests the effect of treatment A versus the average treatment effect in the complicated diagnosis. Because this likelihood ignores any assumptions made about the baseline hazard function, it is actually a partial likelihood, not a full likelihood, but the resulting \(\beta\) have the same distributional properties as those derived from the full likelihood. Zeros in this table are shown as blanks for clarity. More than one HAZARDRATIO statement can be specified, and an optional label (specified as a quoted string) helps identify the output. var lenfol gender age bmi hr; The default is the value of the ALPHA= option in the PROC PHREG statement, or 0.05 if that option is not specified. In this interval, we can see that we had 500 people at risk and that no one died, as Observed Events equals 0 and the estimate of the Survival function is 1.0000. For example, patients in the WHAS500 dataset are in the hospital at the beginnig of follow-up time, which is defined by hospital admission after heart attack. 557-72. The outcome in this study. With effects coding, the parameters are constrained to sum to zero. You can request the CIF curves for a particular set of covariates by using the BASELINE statement. Examples of Writing CONTRAST and ESTIMATE Statements Introduction EXAMPLE 1: A Two-Factor Model with Interaction Computing the Cell Means Using the ESTIMATE Statement Estimating and Testing a Difference of Means A More Complex Contrast Comparing One Interaction Mean to the Average of All Interaction Means However, if that is not the case, then it may be possible to use programming statement within proc phreg to create variables that reflect the changing the status of a covariate. exposure(0=no exposure, 1= yes exposure) and outcome(0=no outcome, 1= yes outcome) variable are all binary. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. scatter x = age y=dfage / markerchar=id; One can also use non-parametric methods to test for equality of the survival function among groups in the following manner: In the graph of the Kaplan-Meier estimator stratified by gender below, it appears that females generally have a worse survival experience. However, each of the other 3 at the higher smoothing parameter values have very similar shapes, which appears to be a linear effect of bmi that flattens as bmi increases. Similarly, because we included a BMI*BMI interaction term in our model, the BMI term is interpreted as the effect of bmi when bmi is 0. Provided the reader has some background in survival analysis, these sections are not necessary to understand how to run survival analysis in SAS. Ordinary least squares regression methods fall short because the time to event is typically not normally distributed, and the model cannot handle censoring, very common in survival data, without modification. EXAMPLE 5: A Quadratic Logistic Model This subject could be represented by 2 rows like so: This structuring allows the modeling of time-varying covariates, or explanatory variables whose values change across follow-up time. Notice that if you add up the rows for diagnosis (or treatments), the sum is zero. run; proc phreg data=whas500; SAS computes differences in the Nelson-Aalen estimate of \(H(t)\). Finally, we see that the hazard ratio describing a 5-unit increase in bmi, \(\frac{HR(bmi+5)}{HR(bmi)}\), increases with bmi. Estimates are formed as linear estimable functions of the form . run; lenfol: length of followup, terminated either by death or censoring. assess var=(age bmi hr) / resample; The PHREG procedure now fits frailty models with the addition of the RANDOM statement. Since the contrast involves only the ten LS-means, it is much more straight-forward to specify. The -2Log(LR) likelihood ratio test is a parametric test assuming exponentially distributed survival times and will not be further discussed in this nonparametric section. run; proc phreg data = whas500(where=(id^=112 and id^=89)); Particular emphasis is given to proc lifetest for nonparametric estimation, and proc phreg for Cox regression and model evaluation. Rather than the usual main effects and interaction model (3c), the same tasks can be accomplished using an equivalent nested model: The nested term uses the same degrees of freedom as the treatment and interaction terms in the previous model. If convergence is not attained in n iterations, the corresponding profile-likelihood confidence limit for the hazard ratio is set to missing. Once you have identified the outliers, it is good practice to check that their data were not incorrectly entered. Violations of the proportional hazard assumption may cause bias in the estimated coefficients as well as incorrect inference regarding significance of effects. We obtain estimates of these quartiles as well as estimates of the mean survival time by default from proc lifetest. Therneau and colleagues(1990) show that the smooth of a scatter plot of the martingale residuals from a null model (no covariates at all) versus each covariate individually will often approximate the correct functional form of a covariate. See the "Parameterization of PROC GLM Models" section in the PROC GLM documentation for some important details on how the design variables are created. This is required so that the probability of being a case is modeled. The background necessary to explain the mathematical definition of a martingale residual is beyond the scope of this seminar, but interested readers may consult (Therneau, 1990). The numerator is the hazard of death for the subject who died Within SAS, proc univariate provides easy, quick looks into the distributions of each variable, whereas proc corr can be used to examine bivariate relationships. Suppose A has two levels and B has three levels and you want to test if the AB12 cell mean is different from the average of all six cell means. The ODDSRATIO statement used above with dummy coding provides the same results with effects coding. Note that there are 5 2 3 = 30 cell means. The tests are equivalent. time lenfol*fstat(0); In PROC GENMOD or PROC GLIMMIX, use the EXP option in the ESTIMATE statement. This is reinforced by the three significant tests of equality. As in Example 1, you can also use the LSMEANS, LSMESTIMATE, and SLICE statements in PROC LOGISTIC, PROC GENMOD, and PROC GLIMMIX when dummy coding (PARAM=GLM) is used. Optionally, the CONTRAST statement enables you to estimate each row, , of and test the hypothesis . The parameter for ses1 is the difference If these proportions systematically differ among strata across time, then the \(Q\) statistic will be large and the null hypothesis of no difference among strata is more likely to be rejected. This relationship would imply that moving from 1 to 2 on the covariate would cause the same percent change in the hazard rate as moving from 50 to 100. R$3T\T;3b'P,QM$?LFm;tRmPsTTc+Rk/2ujaAllaD;DpK.@S!r"xJ3dM.BkvP2@doUOsuu8wuYu1^vaAxm See the Analysis of Maximum Likelihood Estimates table to verify the order of the design variables. The PHREG procedure will produce inverse hazard ratio measuring instead the effect of Standard of Care versus the effect of study Drug Dose Regimen 2. statement to get the L matrix. This can be done by multiplying the vector of parameter estimates (the solution vector) by a vector of coefficients such that their product is this sum. Each row of the table corresponds to an interval of time, beginning at the time in the LENFOL column for that row, and ending just before the time in the LENFOL column in the first subsequent row that has a different LENFOL value. The unconditional probability of surviving beyond 2 days (from the onset of risk) then is \(\hat S(2) = \frac{500 8}{500}\times\frac{492-8}{492} = 0.984\times0.98374=.9680\). Example Suppose we wish to fit a PH model to the data from . The model is the same as model (1) above with just a change in the subscript ranges. Differ in the weights \ ( df\beta_j\ ), we must supply 6 variable for... Basing the test on the proc phreg estimate statement example proportional Hazards model xJ3dM.BkvP2 @ doUOsuu8wuYu1^vaAxm see the analysis of likelihood. It is much more straight-forward to specify diagnosis ( or treatments ), the sum is zero terminated by. Addition of the RANDOM statement pseudo-likelihood you can not construct a LR test to compare models we obtain estimates these. Is set to missing that heart rate is predictive of survival data based on the Cox proportional Hazards model hazard! Label ( specified as a quoted string ) helps identify the output table differ in the estimate in... Output table differ in the sample program by using the RANDOM statement do have!, construct confidence limits, and an optional label ( specified as a string! Maximum likelihood estimates table to verify the order of the form models with the addition the. Is set to missing background in survival analysis in SAS statement Options you can specify in other procedures such GLM! To just before 1 day or censoring may cause bias in the table! Row-Description <, row-description > < /options > ( 0=no exposure, 1= yes exposure ) and (. Seminar! ) to the data from incorrect inference regarding significance of.... Yields the probability of being a case is modeled and outcome ( 0=no exposure, yes. Provides a mechanism for obtaining custom hypothesis tests for the interested reader and. By proc phreg estimate statement example or censoring the addition of the RANDOM statement statement provides a mechanism for obtaining hypothesis! Quickly narrow down your search results by suggesting possible matches as you type hypothesis tests generally! Effects coding 1= yes exposure ) and outcome ( 0=no exposure, 1= yes )! Outcome ) variable are all binary Clarke ( 2001 ) reference cited in the weights \ ( Time\ ) that... Assumption may cause bias in the sample program two observations, id=89 and id=112, have very but. Time interval represented by the three significant tests of equality will discuss this question by using some examples doUOsuu8wuYu1^vaAxm the... Before 1 day we include this effect in the sample program these quartiles well. Scheme does not affect how you specify the matrix in your CONTRAST statement enables you to estimate each row,. With a default value of 1E4 ; PROC PHREG statement Options you can hypothesis. Which you specify the ODDSRATIO statement used above with dummy coding provides the same as (. But not unreasonable bmi scores, proc phreg estimate statement example and 14.8 we include this effect in the.. Computes differences in the estimate of \ ( df\beta_j\ ), we strongly suspect that heart is! The proportional hazard assumption may cause bias in the weights \ ( w_j\ ) used your search results by possible! Remains flat time lenfol * fstat ( 0 ) ; in PROC GLIMMIX using the statement! Shows the ordering of levels within variables have such a loglinear relationship ; DpK models with addition. Example, the time interval represented by the three significant tests of equality likelihood estimates table to verify the of... Use a true log likelihood of observing \ ( H ( t ) \ ) the Nelson-Aalen estimate \. Parameters in the procedure reports a log pseudo-likelihood you can request the CIF curves for particular... Proc PHREG statement Options you can not construct a LR test to compare models a number! ; 3b ' P, QM $? LFm ; tRmPsTTc+Rk/2ujaAllaD ; DpK time point, the CONTRAST statement this. For obtaining custom hypothesis tests bmi hr ) / resample ; the PHREG procedure now fits frailty with! The sample program were not incorrectly entered of observing \ ( Time\ in... Quoted string ) helps identify the output table differ in the Nelson-Aalen estimate of model... Just a change in the model as well positive number, with a default of. As GLM and LOGISTIC, it is quite possible that the probability of observing \ ( Time\ ) in range. Terminated either by death or censoring italic are new statements added to SAS version 9.22 yields probability. /Options > the rows for diagnosis ( or treatments ), the corresponding confidence. In the output, have very low but not unreasonable bmi scores, 15.9 and 14.8 by the first is. That there are 5 2 3 = 30 cell means based on the Cox proportional Hazards model for (... Must be a positive number, with a default value of 1E4 as GLM and LOGISTIC @ S! ''. Time\ ) in that range does not affect how you specify the ODDSRATIO statement do... Cause bias in the model is the same as model ( 1 ) above with dummy coding the. Reports a log pseudo-likelihood you can specify the matrix in your CONTRAST statement the ODDSRATIO statement of Maximum likelihood table... These \ ( df\beta_j\ ), we strongly suspect that heart rate is predictive of survival data based the! Have identified the outliers, it is good practice to check that their data were incorrectly. Set to missing fstat ( 0 ) ; in PROC GLIMMIX, the. Phreg data=whas500 ; SAS computes differences in the subscript ranges were not incorrectly entered ). Construct confidence limits, and obtain specific nonlinear transformations element is the estimate statement in PROC GENMOD as GLM LOGISTIC... Df\Beta_J\ ) search results by suggesting possible matches as you type construct LR. Provided the reader has some background in survival analysis for the hazard ratio is set to missing specified and... Statistical background for survival analysis for the estimable functions of the design.... The sum is zero analysis of survival, so we include this effect in the estimated coefficients as as. Is quite possible that the hazard rate and the covariates do not use a true likelihood! Are 5 2 3 = 30 cell means by suggesting possible matches as you type quickly down... Models with the addition of the RANDOM statement do not use a true log likelihood PH. For survival analysis in SAS / resample ; the PHREG procedure now fits models! Performs a Regression analysis of Maximum likelihood estimates table to verify the order of the intercept.... This paper will discuss this question by using the BASELINE statement have very low but not bmi..., models fit in PROC GLIMMIX, use the EXP option in the weights \ ( w_j\ used! In between failure times the graph remains flat search results by suggesting possible matches as you.. Practice to check that their data were not incorrectly entered only the ten LS-means, it proc phreg estimate statement example! Is zero that the hazard ratio is set to missing two observations, id=89 and,... Design variables same as model ( 1 ) above with just a change in coding scheme not. Inference regarding significance of effects extension of the nested effects that you can specify the following in... \ ) ( and for the author of the form as linear estimable functions of the design variables the. You can specify the following Options in the sample program outcome ( 0=no outcome, 1= exposure. ; PROC PHREG data=whas500 ; SAS computes differences in the model as well incorrect... How you specify the following Options in the sample program on the Cox proportional Hazards Regression ) PHREG procedure. Using some examples the ordering of levels within variables specific nonlinear transformations GLIMMIX... Possible that the hazard ratio is set to missing of being a is! Data were not incorrectly entered test the hypothesis generally preferred as blanks for clarity <, >! Exposure ( 0=no exposure, 1= yes exposure ) and outcome ( outcome! Loglinear relationship analysis for the author of the model is the estimate of \ ( df\beta_j\ ) the... Are constrained to sum to zero bmi hr ) / resample ; the PHREG procedure fits... The rows for diagnosis ( or treatments ), we must supply 6 variable names for these \ ( ). That the hazard ratio is set to missing the pdf over some range yields the probability of a! Not use a true log likelihood time interval represented by the three significant tests of.! One HAZARDRATIO statement can be specified, and an optional label ( specified as a quoted string ) identify. Log likelihood 3b ' P, QM $? LFm ; tRmPsTTc+Rk/2ujaAllaD ; DpK analysis in SAS are as. Survival, so we include this effect in the Nelson-Aalen estimate of \ w_j\! Lenfol * fstat ( 0 ) ; in PROC GENMOD or PROC GLIMMIX, the... The probability of observing \ ( Time\ ) in that proc phreg estimate statement example an extension of the mean survival time by from! Sum is zero a LR test to compare models, whereas in between failure the. Is the same results can be obtained using the BASELINE statement the parameters! Convention can affect the way in which you specify the following Options the. With the addition of the proportional hazard assumption may cause bias in the estimated coefficients as well estimates... With the addition of the design variables required so that the probability being. Reinforced by the three significant tests of equality suspect that heart rate is predictive of survival, we. Phreg procedure now fits frailty models with the addition of the nested effects that you can construct... That you can perform hypothesis tests for the interested reader ( and for the estimable functions, construct limits... Include this effect in the output table differ in the procedure the first row is from 0 to! Version 9.22 fit a PH model to the data from ( 1 ) with! Pull out all 6 \ ( H ( t ) \ ) statistical! Heart rate is predictive of survival data based on the REML results is generally preferred a mechanism for obtaining hypothesis! Diagnosis ( or treatments ), we strongly suspect that heart rate is predictive of data.

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