The beta level (often simply called beta) is the probability of making a Type II error (accepting the null hypothesis when the null hypothesis is false). It is directly related to power, the probability of rejecting the null hypothesis when the null hypothesis is false. Power plus beta always equals 1.0.
Frequently researchers will select a sample size and decision rule to insure that beta is 0.20 or less (or equivalently power is 0.80 or more). Some researchers prefer to insure that the beta level is 0.10 or less.
Example: In a study of two interventions to prevent hypothermia during liver transplantation, the researchers designed the study so that the beta level was 0.2.
A minimum sample size of 24 total subjects was calculated as needed to be enrolled and analyzed to detect a clinically relevant difference in the primary outcome of mean rectal or esophageal temperatures (temperature difference 0.5°C between the groups) according to the power analysis based on following parameters: type II error rate- (beta = 0.2), type I error rate (alpha = 0.05, d = 0.5, sigma = 0.4). -- Water warming garment versus forced air warming system in prevention of intraoperative hypothermia during liver transplantation: a randomized controlled trial [ISRCTN32154832]. Janicki PK, Stoica C, Chapman WC, Wright JK, Walker G, Pai R, Walia A, Pretorius M, Pinson CW. BMC Anesthesiol 2002: 2(1); 7. [Medline] [Abstract] [Full text] [PDF]
FAQs
In general, a baseline beta hCG level >100 mIU/mL is generally considered a good, positive result.
What is a good hCG level to confirm pregnancy? ›
How do you know if your hCG is positive?
| Weeks from the last menstrual period (LMP) | Approximate amount of hCG (in mIU/mL or IU/L) |
|---|
| 13-16 weeks | 3,300-253,000 |
| 17-24 weeks (second trimester) | 4,060-165,400 |
| 25 weeks to term (third trimester) | 3,640-117,000 |
| After several days (up to 2 weeks) postpartum | <5 |
6 more rowsUrine tests.
At-home urine tests require higher levels of hCG to detect a pregnancy, typically at least 20 mIU/mL.
What is a normal hCG free beta level? ›
Results are given in milli-international units per milliliter (mUI/mL). Normal levels are found in: Non-pregnant women: less than 5 mIU/mL. Healthy men: less than 2 mIU/mL.
What is a good hCG level at 5 weeks? ›
hCG blood levels by week
| Length of pregnancy | Average hCG levels in blood during pregnancy |
|---|
| 5 weeks | 200 - 7,000 µ/L |
| 6 weeks | 200 - 32,000 µ/L |
| 7 weeks | 3,000 - 160,000 µ/L |
| 8 - 12 weeks | 32,000 - 210,000 µ/L |
4 more rowsIf the Beta HCG value are inbetween 0-5, that means pregnancy did not occur. Values such as 0.1 and 1.20 can be seen.
What should hCG be at 1 week pregnant? ›
An hCG level of less than 5 mIU/mL is considered negative for pregnancy, and anything above 25 mIU/mL is considered positive for pregnancy. An hCG level between 6 and 24 mIU/mL is considered a grey area, and you'll likely need to be retested to see if your levels rise to confirm a pregnancy.
What is the minimum hCG level for pregnancy? ›
hCG Levels Chart
| Weeks From Last Menstrual Period (LMP) | hCG Level in milli-international units per milliliter (mIU/mL) |
|---|
| 3 weeks from LMP | 5–50 mIU/mL |
| 4 weeks from LMP | 5–426 mIU/mL |
| 5 weeks from LMP | 18–7,340 mIU/mL |
| 6 weeks from LMP | 1,080–56,500 mIU/mL |
5 more rowsMar 27, 2024
It has been previously suggested (10) that a 53% rise after 2 days will identify 99% of pregnancies that are viable, when the initial hCG <5000 mIU/mL. The current data suggest that this is likely true for women with an initial hCG value below 1500.
What is borderline pregnancy? ›
A borderline result is generated by some assays when the hCG level is between 5 and 25 mIU/mL. Samples reported as borderline are considered indeterminate, and clinicians should request a repeat test within 48 to 72 hours or obtain a quantitative serum hCG.
A gestational sac is predicted to be visualized 50% of the time at an HCG level of 979 mIU/mL, 90% at 2421 mIU/mL, and 99% of the time at 3994 mIU/mL.
What is the hCG level for a single baby? ›
HCG levels from normal singleton pregnancies (and twins below)
| Day after HCG or LH | Average mIU/ml | High mIU/ml |
|---|
| 14 | 48 | 119 |
| 15 | 59 | 147 |
| 16 | 95 | 223 |
| 17 | 132 | 429 |
7 more rowsIn general, a beta hCG level of over 100 is generally considered a good, positive result. But what's more important than the absolute beta number that helps determine normal levels is the rate of increase over time (it should double every 48 hours).
What is a positive beta hCG? ›
Beta hCG blood test results are considered positive for pregnancy when they are > 5 mlU/mL. Higher concentrations of hCG, typically at least 20 mIU/mL, are needed for at-home urine tests to identify pregnancy.
What hCG level indicates twins? ›
Range of hCG levels and what they can mean
The range for singletons is 5 – 397 and for twins it is 48 – 683. As you can see, there is a big overlap between the first hCG level in singleton and twins. What this means is that even if you have a first hCG level of 397, it could be a singleton pregnancy.
What is a good beta score? ›
High-beta stocks, which generally means any stock with a beta higher than 1.0, are supposed to be riskier but provide higher return potential; low-beta stocks, those with a beta under 1.0, pose less risk but also usually lower returns.
What is an acceptable beta value? ›
Values of beta should be kept small, but do not have to be as small as alpha values. Values between . 05 and . 20 are acceptable.
Is a beta of .5 good? ›
A beta lower than one suggests that a stock is less risky than the market. A beta of . 5 suggests that the stock is 50% less volatile than the market. Adding this type of stock to a portfolio lowers the overall risk but has a similar effect on potential return.
What should be ideal beta? ›
Theoretically, the beta value of a benchmark index is considered to be 1. The risk factor of securities is evaluated around this number, wherein a stock having a beta coefficient higher than 1 is deemed to be a risky investment venture.
