how to create effective surveys

Thousands of books and articles have been written about survey methodology, but in case you don’t have hours to devote to becoming a guru, here are ten best practices to consider when building and distributing your survey.

1. Make Sure That Every Question Is Necessary

You’re building your survey to obtain important insights, so every question in the survey should play a direct part. It’s best to plan your survey by first identifying the data you need to collect and then writing your questions.

2. Keep it Short and Simple

Respondents are less likely to complete long surveys, or surveys that bounce around haphazardly from topic to topic. Therefore, make sure your survey follows a logical order and that it takes a reasonable amount of time to complete.

3. Ask Direct Questions

Vague or poorly worded questions confuse respondents and make your data less useful. Strive for clear and precise language that will make your questions easy to answer.

See an example:

4. Ask One Question at a Time

Take a closer look at questions in your survey that contain the word “and”—it can be a red flag that your question has two parts. Here’s a sample: “Which of these cell phone service providers has the best customer support and reliability?” In this case, a respondent may feel that one service is more reliable, but another has better customer support.

See an example:

5. Avoid Leading and Biased Questions

Some descriptive words and phrases may interject some bias into your questions, or point the respondent in the direction of a particular answer. In particular, scrutinize adjectives and adverbs in your questions. If they’re not needed, take them out.

In addition, an unbalanced response scale can lead a respondent in the same way a poorly worded question might. Make sure your response scales have a definitive midpoint (aim for odd numbers of possible responses) and that they cover the whole range of possible reactions to the question.

See an example:

6. Speak Your Respondent’s Language

Use language and terminology that your respondents will understand. Make words and sentences as simple as possible and avoid technical jargon. However, don’t oversimplify a question to the point that it will change the way the question will be interpreted.

See an example:

7. Use Response Scales Whenever Possible

Response scales that give the direction and intensity of attitudes provide rich data. By contrast, categorical or binary response options, such as true/false or yes/no response options, generally produce less informative data.

Avoid using scales that ask respondents to agree or disagree with statements, however. Some people are biased toward agreeing with statements, and this can result in invalid and unreliable data.

See an example:

8. Avoid Using Grids or Matrices for Responses

Oftentimes respondents don’t fill in grids correctly or accurately according to their true feelings. Also, grids aren’t mobile-friendly. It’s better to separate questions with grid responses into multiple questions in your survey with regular response scales.

See an example:

9. Rephrase Yes/No Questions if Possible

Many yes/no questions can be reworked by including phrases such as “How much,” “How often,” or “How likely.” Make this change whenever possible and include a response scale for richer data.

See an example:

10. Take Your Survey for a Test Drive

Ask at least five people to test your survey to help you catch and correct problems before you distribute.

Reference: 

https://www.qualtrics.com/blog/10-tips-for-building-effective-surveys/

Multiple Dosage Regimen

Drug kinetics after multiple dosing

Pharmacokinetics of multiple dose

•     The purpose of the multiple dosing is to maintain a desired plasma level of drugs for long periods of time.

•     The plasma level obtained from each succeeding dose is always higher than those obtained from the previous dose since some drug remains in the plasma when repeated doses are administered. • Since the rate of elimination is proportional to the amount of drug in the body, it increases with the increasing amount of drug until it approaches the rate of input (rate of input=rate of output). • At this point the amount reaches a plateau in the body. (Rate of input=rate of output).

•     The main difference is the fluctuation in the plasma concentration due to multiple dosing.

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•              Dosage regimen: – size of the drug dose – frequency of drug administration, i.e. time interval between doses (τ: tau) •              Pharmacokinetic parameters obtained from single dose administration are used to predict drug plasma levels during a multiple-dosage regimen. • The principle of superposition assumes that early doses of drug do not affect the pharmacokinetics of the subsequent doses. 11/3/2015                                                                                                                                            5

•     AUC0-∞= AUC0-τ

•     If the drug is administered at a fixed dose and fixed dosing interval (τ), the amount of the drug in the body will increase and then plateau to a mean plasma level higher than the peak Cp obtained from the first dose.

•     This is known as “steady state”, at which the plasma drug levels fluctuate between Cpss^max and Cpss^min

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•  The average Cpssav is calculated by dividing the AUC for a dosing interval (AUC0-τ) by τ, at steady state •  Regardless of the route of administration: Cpssav = F×D0 = F×D0 = AUCss0−τ = AUC0−∞                   CL×τ Vd×kd×τ      τ           τ •  Accumulation factor (R): Cpssmax  Cpssmin      =    max = min =            C1 C1      1−e 11/3/2015                                                                                                                                            7

•  The maximum accumulation of drug in the body can be given in terms of the administered dose as: 1.44 t           X/Xo =  =   1/2    , where: X: is the maximum drug accumulation Xo: is the amount after first dose                                                                                                                                                                                                                    : dosing interval •  Therefore, when the dosing interval is equal to the half-life of the drug, the maximum accumulation will be 1.44 times the administered dose. 8

•     As the frequency of dosing increases the accumulation level also increases.

•     For example:

If the dosing interval is one-fourth the half-life, the maximum accumulation is 5.76 times the administered dose.

•     Therefore, a desired plateau level can be achieved either by:

– Selecting a dosing interval and adjusting the dose or – By changing the dosing interval to give a fixed dose

•     Drug accumulation is not a phenomenon that depends on the property of a drug.

•     Accumulation is the result of the frequency of administration relative to half-life.

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•   Some fluctuation is always present and the percentage of fluctuation is given by:                                %       =                        ( − ) •   This means that the fluctuation in the plasma concentration is only a . function of the drug half life ( . = ) or the dosing interval. •   Since the half life of drug is constant, the adjustment in the dosing interval is required to achieve desired fluctuation. •   If a drug is administered more frequently (smaller τ), the fluctuation decreases and reaches a limit of (0) percent fluctuation when the dosing interval is zero as in the case of constant intravenous infusion.       11/3/2015                                                                                                                                            11
•	For a given drug in multiple-doses, the time required to reach steady state is dependent on the t1/2 of the drug and is independent of the size of the dose, length of τ, and number of doses.
•	For a drug given at the same dosing rate (e.g. 20 mg/h: 120 mg/6h, 240 mg/12h, or 480 mg/24h), the Cpssav will be the same, but fluctuation between Cpssmax and Cpssmin will vary. 12

•  The rate with which the plateau level is reached is dependent only on the elimination half-life. •  It will therefore take one half-life to reach 50% of the plateau level (Cpss), and 3.3 half-lives to reach 90% of the maximum level.                               × = × (1 − ×) tss (90%) = ‒ ln(0.1)/ k = 3.3 t1/2 11/3/2015                                                                                                                                          13

•  At steady state: Rate in (input) = Rate out (output) F×D/τ= CL×Cpss •  Regardless of the route of administration: Cpssav = F×D = F×D = AUC0−τ = AUC0−∞                 CL×τ Vd×kd×τ     τ          τ 14

•   Following multiple dosing, the plasma concentration can be estimated by using the following equation: = D 0 1− e− nkτ × −kt      Cp t                ( − −kτ ) e                     Vd  1   e , where: n = number of doses given, and t = time after nth dose •   As the number of doses (n) approaches infinity (∞), a plateau (steady state) is reached at which the plasma concentration at any time t (post dose) can be estimated by the following equation:                        D   1 Cpss = 0 ( − −kτ )×e−kt Vd 1 e 11/3/2015                                                                                                                                          15

D                                 Cp   0 Cpssmax= −0kτ ;Cpssmax = −eVd−kτ                             1−e 1 Cpssmin = Cp−0kτ ×e−kτ =Cpssmax ×e−kτ 1−e 16

•  For a continuous i.v. infusion: Cpt = R (1−e−kt )= R            (1−e−kt ) CL    Vd×kd •  After one or more short i.v. infusions: D Cp t =  (1 − e−kt )      (modified from above) tinf ×Vd × kd •  After the infusion is stopped: Cp t = C stop ×e− kt 11/3/2015                                                                                                                                          17

• For multiple oral dose regimen: –  Before reaching the steady state:             t F×ka×D0 ⎢⎡ 1−−ee−−nkakaττ ×e−kat −(11−−ee−−nkkττ)×e−kt ⎤⎥⎦      Cp =             (       ) Vd(k−ka) ⎣ 1 –  At steady state: Cpss= F×(ka×D)0 ⎡⎢⎣(1−1e−kτ)×e−kt −(1−1e−kaτ)×e−kat ⎤⎦⎥ Vd ka−k 18

Cpssmax = F×D0 ( 1−kτ )×e−ktp                                 Vd 1−e Cpssmin = ka×F×D0 ( 1−kτ )×e−kτ Vd(ka−k) 1−e 11/3/2015                                                                                                                                          19

•  Following a single oral dose: tmax = 2.3 ×log ka ka −k       k •  At steady state: tp(tmax, ss) = 1 ×ln⎡⎢ka×(1−e−−kakττ)⎤⎥ ka−k ⎢⎣k×(1−e )⎥⎦ 20

Loading dose (Priming dose) •              It is the dose that provides an effective concentration in the plasma instantaneously • The main objective of the loading dose is to achieve the desired (therapeutic) concentration as quickly as possible. •              Oral DL can be calculated as follows:                        DL0 = ka −e k )                          D (1−e      )(1 11/3/2015                                                                                                                                          21

Loading dose •  For extremely rapid absorption or in the case of IV infusion:                                   DL = 1−kτ                                    D0   (1−e    ) •  As a general rule, the dose ratio should be equal to 2 if the selected dosage interval τ = t1/2 D Dose ratio = L D0 22

• A rapid approximation of DL may be estimated from the following equation: = Vd ×Cpssav     Loading dose (DL) (S)(F) ,where: S: fraction of the administered dose which is the active form of the drug F: bioavailability of the drug 11/3/2015                                                                                                                                          23

•  After multiple dosing, the maintenance dose required is based on CL, Cpss, dosing interval (τ): CL×Cpssav ×τ Maintenance Dose (D0) = (S)(F) ,where: S: fraction of the administered dose which is the active form of the drug F: bioavailability of the drug •  When Cpss & τ are fixed, a drug with a smaller CL would require a smaller maintenance dose. 11/3/2015                                                                                                                                          25

3- Check your calculations: By         applying    these equations	to	find	the
corresponding Cpssmin & Cpssav 11/3/2015			27
• Factors that should be considered in designing a dosage regimen: 1.  Activity and toxicity: ¾ Minimum therapeutic dose ¾ Toxic dose ¾ Therapeutic index (Therapeutic window) ¾ Side effects ¾ Dose-response relationships 2.  Pharmacokinetic processes of drugs which can be influenced by dosage form: ¾ Absorption ¾ Distribution (ADME) ¾ Metabolism ¾ Excretion 3.  Clinical state of patients: ¾ Age, Weight, Urine pH, Condition being treated, Existence of other diseases. 4.  Other factors: ¾ Tolerance ¾ dependence ¾ Drug interactions 11/3/2015			28

Reference • Applied Biopharmaceutics & Pharmacokinetics by Leon Shargel, Susanna Wu-Pong (4th edition): Chapters 15 & 17 11/3/2015                                                                                                                                            29