Package 'rollmatch'

Preprocessing Step to Rolling Entry Matching

Description

Preprocessing Step to Rolling Entry Matching

Usage

reduce_data(data, treat, tm, entry, id, lookback = 1)

Arguments

data	Original dataset before reduce_data() was ran.
treat	String for name of treatment variable in data.
tm	String for time period indicator variable name in data.
entry	String for name of time period in which the participant enrolled in the intervention (in the same units as the tm variable).
id	String for individual id variable name in data.
lookback	The number of time periods to look back before the time period of enrollment (1-...).

Value

reduced_data returns a dataset of reduced data ready for propensity scoring and to use in the function score_data()

Examples

data(package="rollmatch", "rem_synthdata_small")
reduced_data <- reduce_data(data = rem_synthdata_small, treat = "treat",
                            tm = "quarter", entry = "entry_q",
                            id = "indiv_id", lookback = 1)
reduced_data

---

Synthetic dataset to illustrate rolling entry

Description

This dataset represents a synthetic population of individuals who resemble Medicare fee-for-service patients in terms of age, race, spending, inpatient visits, ED visits, chronic conditions, and dual eligibility. The quasi-panel dataset contains multiple observations of non-participants (one for each entry period). Participants enter the data once in the baseline period immediately preceding their unique entry into the intervention. Time-varying covariates (e.g., health conditions, spending, utilization) are dynamic for each entry period's non-participant observations.

Usage

rem_synthdata

Format

A data frame with 254,400 observations and 20 variables:

indiv_id

The unique identifier for each individual.

entry_q

The period in which the individual enrolled in treatment / entered the intervention.

lq

Last baseline quarter before entry into the intervention.

quarter

Time variable, indicating the quarter that the variables are measured.

treat

Treatment indicator variable (=1 if in treatment group and =0 if in control group).

age

The patient's age.

is_black

Race indicator variable (=1 if identified as Black, =0 if not).

is_disabled

Physical disability indicator variable (=1 if identified as disabled, =0 if not).

is_esrd

Disease indicator variable (=1 if identified as having End Stage Renal Disease (ESRD), =0 if not).

is_hispanic

Ethnicity indicator variable (=1 if identified as Hispanic, =0 if not).

is_male

Gender indicator variable (=1 if identified as Male, =0 if not).

is_white

Race indicator variable (=1 if identified as White, =0 if not).

lq_ed

Indicates the person had an ED visit during LQ.

lq_ip

Indicates the person had an inpatient stay during LQ.

yr_ed2

Count of ED visits during quarters LQ-5 to LQ-1.

yr_ip2

Count of inpatient stays during quarters LQ-4 to LQ-1.

months_dual

Number of months of dual Medicare-Medicaid eligibility in the previous year.

chron_num

Number of chronic conditions.

qtr_pmt

Payments during the quarter.

yr_pmt

Payments during the previous 4 quarters.

---

Synthetic dataset to illustrate rolling entry (small)

Description

This dataset represents a synthetic population of individuals who resemble Medicare fee-for-service patients in terms of age, race, spending, inpatient visits, ED visits, chronic conditions, and dual eligibility. The quasi-panel dataset contains multiple observations of non-participants (one for each entry period). Participants enter the data once in the baseline period immediately preceding their unique entry into the intervention. Time-varying covariates (e.g., health conditions, spending, utilization) are dynamic for each entry period's non-participant observations. This is a smaller version of rem_synthadata.

Usage

rem_synthdata_small

Format

A data frame with 12,720 observations and 20 variables:

indiv_id

The unique identifier for each individual.

entry_q

The period in which the individual enrolled in treatment / entered the intervention.

lq

Last baseline quarter before entry into the intervention.

quarter

Time variable, indicating the quarter that the variables are measured.

treat

Treatment indicator variable (=1 if in treatment group and =0 if in control group).

age

The patient's age.

is_black

Race indicator variable (=1 if identified as Black, =0 if not).

is_disabled

Physical disability indicator variable (=1 if identified as disabled, =0 if not).

is_esrd

Disease indicator variable (=1 if identified as having End Stage Renal Disease (ESRD), =0 if not).

is_hispanic

Ethnicity indicator variable (=1 if identified as Hispanic, =0 if not).

is_male

Gender indicator variable (=1 if identified as Male, =0 if not).

is_white

Race indicator variable (=1 if identified as White, =0 if not).

lq_ed

Indicates the person had an ED visit during LQ.

lq_ip

Indicates the person had an inpatient stay during LQ.

yr_ed2

Count of ED visits during quarters LQ-5 to LQ-1.

yr_ip2

Count of inpatient stays during quarters LQ-4 to LQ-1.

months_dual

Number of months of dual Medicare-Medicaid eligibility in the previous year.

chron_num

Number of chronic conditions.

qtr_pmt

Payments during the quarter.

yr_pmt

Payments during the previous 4 quarters.

---

Rolling entry matching

Description

rollmatch is the last of 3 main functions in the rollmatch package <rollmatch> implements a comparison group selection methodology for interventions with rolling participant entry over time. A difficulty in evaluating rolling entry interventions is that a suitable "entry" date is not observed for non-participants. This method, called rolling entry matching, assigns potential comparison non-participants multiple counterfactual entry periods which allows for matching of participant and non-participants based on data immediately preceding each participant's specific entry period, rather than using data from a fixed pre-intervention period.

Usage

rollmatch(
  scored_data,
  data,
  treat,
  tm,
  entry,
  id,
  vars,
  lookback,
  alpha = 0,
  standard_deviation = "average",
  num_matches = 3,
  replacement = TRUE
)

Arguments

scored_data	Output from scored_data() or the output from reduce_data() with propensity scores labeled "score".
data	Original dataset before reduce_data() was ran.
treat	String for name of treatment variable in data.
tm	String for time period indicator variable name in data.
entry	String for name of time period in which the participant enrolled in the intervention (in the same units as the tm variable).
id	String for individual id variable name in data.
vars	Vector of column names used in the propensity score algorithm. This is used when creating the balance table.
lookback	The number of time periods to look back before the time period of enrollment (1-...).
alpha	Part of the pre-specified distance within which to allow matching. The caliper width is calculated as the alpha multiplied by the pooled standard deviation of the propensity scores or the logit of the propensity scores - depending on the value of match_on.
standard_deviation	String. 'average' for average pooled standard deviation, 'weighted' for weighted pooled standard deviation, and 'None' to not use a standard deviation multiplication. Default is "average".
num_matches	Number of comparison beneficiary matches to attempt to assign to each treatment beneficiary. Default is 3.
replacement	Assign comparison beneficiaries with replacement (TRUE) or without replacement (FALSE). If replacement is TRUE, then comparison beneficiaries will be allowed to be used with replacement within a single quarter, but will not be allowed to match to different treatment beneficiaries across multiple quarters. Default is TRUE.

Details

Rolling entry matching requires preliminary steps. This package will assist the user in steps 2 and 3. First, a quasi-panel dataset is constructed containing multiple observations of non-participants (one for each entry period). Participants enter the data once in the baseline period immediately preceding their unique entry into the intervention. Time-varying covariates (e.g., health conditions, spending, utilization) are dynamic for each entry period's non-participant observations. The user of rollmatch is expected to have already created this quasi-panel dataset. Second, the pool of potential comparisons for each participant is restricted to those that have the same "entry period" into the intervention (see function "reduce_data"). Finally, a predicted probability of treatment is obtained for participants and non-participants (e.g. through propensity score matching). The user can use function "score_data" to complete this step, or create use their own propensity score calculation.

The final step consists of the matching algorithm. The algorithm selects the best matched comparison(s) for each participant from the pool of non-participants with the same entry period. This is completed via the function "rollmatch".

Value

rollmatch returns an object of class "rollmatch".

An object of class "rollmatch" is a list containing the following components:

model	The output of the model used to estimate the distance measure.
scores	The propensity scores used in the matching algorithm.
data	The original dataset with all matches added.
summary	A basic summary table with counts of matched and unmatched data.
ids_not_matched	A vector of the treatment IDs that were not matched.
total_not_matched	The number of treatment IDs not matched.
matched_data	R data.frame of matches with scores, matching information, and the weights of the individuals
balance	table showing the full treatment, full control, matched treatment, and matched comparison group means and standard deviations for the variables used in the model.

Examples

data(package="rollmatch", "rem_synthdata_small")
reduced_data <- reduce_data(data = rem_synthdata_small, treat = "treat",
                            tm = "quarter", entry = "entry_q",
                            id = "indiv_id", lookback = 1)
fm <- as.formula(treat ~ qtr_pmt + yr_pmt + age)
vars <- all.vars(fm)
scored_data <- score_data(reduced_data = reduced_data,
                          model_type = "logistic", match_on = "logit",
                          fm = fm, treat = "treat",
                          tm = "quarter", entry = "entry_q", id = "indiv_id")
output <- rollmatch(scored_data, data=rem_synthdata_small, treat = "treat",
                    tm = "quarter", entry = "entry_q", id = "indiv_id",
                    vars = vars, lookback = 1, alpha = .2,
                    standard_deviation = "average", num_matches = 3,
                    replacement = TRUE)
output

---

Create propensity scores using a logistic or probit regression model

Description

Create propensity scores using a logistic or probit regression model

Usage

score_data(reduced_data, model_type, match_on, fm, treat, tm, entry, id)

Arguments

reduced_data	Dataframe of reduced treatment and comparison data. See output of reduce_data().
model_type	Use logistic regression ("logistic") or "probit" regression ("probit") to estimate the predicted probability of participating
match_on	Match on estimated propensity score ("pscore") or logit of estimated propensity score ("logit").
fm	A formula in the form treat ~ x1 + x2 ... where treat is a binary treatment indicator (Treat = 1, Control = 0) and x1 and x2 are pre-treatment covariates. Both the treatment indicator and pre-treatment covariates must be contained in the input dataset.
treat	String for name of treatment variable in data.
tm	String for time period indicator variable name in data.
entry	String for name of time period in which the participant enrolled in the intervention (in the same units as the tm variable).
id	String for individual id variable name in data.

Value

A copy of reduced_data input with added propensity scores

Examples

## Not run: 
data(package="rollmatch", "rem_synthdata_small")
fm <- as.formula(treat ~ qtr_pmt + age + is_male + is_white)
reduced_data <- reduce_data(data = rem_synthdata_small, treat = "treat",
                            tm = "quarter", entry = "entry_q",
                            id = "indiv_id", lookback = 1)
scored_data <- score_data(reduced_data = reduced_data,
                          model_type = "logistic", match_on = "logit",
                          fm = fm, treat = "treat", tm = "quarter",
                          entry = "entry_q", id = "indiv_id")
head(scored_data)

## End(Not run)

---